do i have a case if I was fired for missing a call on the on call phone while driving.

Four weeks ago I put in a formal complaint about verbal and physical harrassment from a co-worker. This co-worker is a favorite of the president of the company and did nothing when I put in the complaint. I then submitted another formal complaint to my immediate supervisor who gave it to the legal deparment within the company. I have statements from former employees about how they have witnessed her harrassing me, along with recordings of one former employee and one current(supervisor) employee stating that they have told the president that she harrasses me on a daily basis and she is the cause of all the chaos in the office and how she treats certain people very poorly because the president makes her feel untouchable (they were not aware I was recording). They flew someone in from the head quarters HR department to investegate. That same day of the investigation the president calls my office phone and says, "where is my favorite person, where's Jen." Jen is the person that has been harrassing me and the president was trying to intimidate me by letting me know she will be left alone and not diciplined. My contract stats that on occasion I will be on call. I have been on call all week every other week in the past month and a half. 4 weeks after making the complaint, I received a call on the oncall cell phone we use while driving in my car. I arrived at my distination 25 minutes after the phone call. Jen was called after I wasn't able to be reached and then Jen soon called the president and the president called me on the on call phone, I explained to him that I was driving after having to pick up my little girl from her after school activity and reminded him that it is illegal to drive and talk on the phone. He yelled and said you are on call and are suppose to always answer the cell phone no matter where you are. 2 hours later I got a call from the headquarters hr department telling me that the president says to not show up for work tomorrow for missing a on call phone call. There have been many oncall calls missed by others, never was anyone fired for not being able to answer a call. Also before the formal complaint put in, there have been many turn overs with office managers,6 in less than one year, the last two stated to me that Jen had asked the president to fire me and he told her to try and get the office manager to agree to it and that is fine. After Jen asked the executive director and office manager to fire me they both said no and said that "she does her job well and there is no basis for me firing her, she is a quite person who everyone likes and doesn't do anything wrong. The executive director was fired for not firing people he felt did nothing wrong and so was the office manager. The executive director sent me textes telling me that the president was told by Jen that I am friends with the first office manager and that I shouldn't work there anymore because of this, the executive director told me that the president told him that he thinks I might be mad at him for firing the first office manager and report him to medicare fraud for the double billing I inquired with him on and shouldn't be here no matter how good of a job she is doing.(he said to the director.."i dont trust her being friends with the first office manager, this distrust was feed to him by Jen. I was also told by the current supervisor that the president asked Jen to post my position back up and interview people back in april, I had done nothing wrong and my work was always done and never written up for anything. I was told I was fired the day before the exact date that would have been my year anniversary which allows more benefits and other oppurtunities. I also should explain what was involved in the harrassment form that I submitted. I reported her shoving me out of her way when I was filling things in filing cabinet because she was mad at me for sticking up for myself when she tried to get the supervisor to write me up for something she admitted she did not know was minimized on my screen. she called me into the supervisors office and said, "I saw a word document minimized on your computer and I think you are doing homework while at work." when I told her she should have asked me what it was when she was in my office instead of assuming it was school work because it wasn't and that I deal with work word documents everyday. the supervisor told jen that she can't write me up for something she thinks she saw. She got really red and stormed out of the room, then later on that day is when she shoved me into the filing cabinets when I was taking up to much room between the hallway and the filling cabenits. Also she called me to come into her office to be a witness to someone sleeping at there desk, I walked into her office while passing the persons office that she was talking about, I told her she wasn't sleeping, she then said go ask her a question and see if she answers in a tired manner because she thought she was acting some what "out of it" and wanted a witness, I told her that I wasn't going to be involved in her trying to get other people in trouble and that as a HR person she should ask her instead if she is ok. Jen turned away from me and called me a "bitch". What I listed in the complaint goes on and on. This person is amazing with the things she feels as though she can do to certain people, especially me. I also stated in the formal complaint that I confronted her on her treatment toward me and asked what, if any, is the problem that she seems to have with me and I gave her examples, the only response I got from her is her saying, "I just think you are to quite and you need to talk more. Do I have a case if my contract states that I have 15 minutes to give a return call when oncall, which I did but still was fired for missing a call, getting fired for missing a call is not in the contract...does this sound like a case that a lawyer will take on a contingency base and if so can you recommend one in minnesota.