BUILDER SENDS ME AN ADDENDUM TRYING TO CHANGE THE TERMS OF THE CONTRACT FROM A SET PRICE TO COST PLUS 7.5 %, HAS STOPPED WORK BECAUSE I HAVE REFUSED TO SIGN. I DON'T KNOW WHAT HIS COSTS ARE, HE CAN PUT ANY PRICE ON THAT ADDENDUM. THE CONTRACT STATES 7 MONTHS FOR COMPLETION, THAT TIME PERIOD WILL BE UP IN 2 WEEKS, HE HASN'T EVEN POURED THE SLAB. WHAT DO I DO?