Does change in pay constitute breach of contract?

Hello!
A handful of us had to move to keep our jobs with our company. We signed two agreements with our move. They are pretty straightforward, and no fine print. One was a relocation agreement which is about ten sentences long. It is an 18 month contract. We were each given money for a relocation bonus. The amount depended on if we rented or owned a home. It clearly states that the contract does not guarantee employment, and that if we quit or are fired we owe the money back immediately and will incur legal fees if we do not promptly pay. The second document we signed was for pay. Our pay is hourly plus commission, and we are sales people. We all make individual houlry wages based on time with the company and performance. What we all signed was for our commission plan. This was last year in August and we are just over halfway through. Two weeks ago, our department's commission was literally slashed in half. Human resources was involved in meetings we had to discuss the new plan and we were forced to sign the new plan. We are thinking this is clearly a breach of our contract and would make even the relocation agreement null and void. None of us can even afford to live in our new surroundings due to the cost of living (we made more than plenty of money on the old plan to be more than comfortable). I have tried searching Wisconsin statutes and am finding nothing. Any info or a point in the right direction would be helpful!

(I just had a consult with an employment lawyer. Even though we were "forced" to sign the new pay agreement, we still signed, and we entered into a new contract. I cannot seem to delete my question, so just wanted to say I had it answered. Thank you in advance for you time. I apologize for any inconvenience).