Foundation Repair / Monthly payment amount!

Basement Systems (Michigan) installed foundation repair in my home. There have been a myriad of problems throughout the process including three different price quotes and the attempt to install a $10,000.00 job BEFORE financing was secured. I had told inspector Steve Ray from the start I could only afford to finance repair of the side wall without excavation. The job was finally completed with many misunderstandings along the way. The employees like to call this "bad communication". I was also assured that my monthly payment amount would be $87.00. However, GEMoney Bank tells me that my payment will be $150.00 a Month. Essentially twice the amount Basement Systems promised it would be.