Mariko is having a house built. After the specifications for the house have been provided to the contractor, the contract has been signed and the contractor has begun to build the house, Mariko demands that the contractor add beneath her bedroom floor, heating coils to heat the floor, and floor lights which will light her path to the bathroom during the night. These additions were not in the original agreement. The contractor refuses. Is this a breach of contract? Why or why not? Does Mariko have any recourse? Explain.