At-Will? Wrongful Termination?

I live in San Jose, Ca. California currently abides by "at-will" employment laws, supposedly allowing an employer to terminate an employee's position for any reason. But. . . .


I work(ed) in an auto dealership where, as part of my compensation package, I was given a used car "demo" to drive. It was, at one point, decided that no employee was to receive a demo. This resulted in an initial need for immediate transportation. December 21st (while at work), I was permitted by my General Sales Manager (GSM) to complete my new car purchase at another dealership. The process took much longer than I'd expected and was not able to arrive back at work until near closing time. An employee who normally covers my office (days off & such) had come by & was taking care of the customers waiting in my office. She said she would finish the paperwork in regards to this particular deal; and so I left. I had previously attained permission by my GSM to take 12/22-12/27 as vacation time (unpaid). Having been enlightened by co-employees, I met my GSM at our place of business on 12/27, where he commenced to terminate my employment, effective 12/21. Now, I know (generally) I can be let go for any reason, and have no recourse. However, if I am terminated for a specific reason, and that reason is blatantly false, do I, at this point, have any avenues of recourse?

Also, the time-line being followed to pay my final earned wages doesn't seem quite right:
12/21 Effective date of termination
12/27 Termination paperwork completed
01/07 My "supposed" final check
01/28 A portion of my STILL unpaid wages were paid
02/17 I am still owed several thousand dollars in unpaid wages; it's been nearly 2 months, I'm about to go into foreclosure, and can't seem to get much help from my ex-employer.

What should I do? Any help at all would be huge for me right now.

Thanks SOOO much!