Shasha was engaged to produce 100 sets of uniform to one kindergarten. She was given two weeks to settle the order of the uniform and make delivery to the kindergarten within the two weeks. After 10 days, she had delivered 75 sets of uniform and promised to deliver the balance within five days. However, after four days, the kindergarten still has not received the uniform. In the meantime, Shasha had sent a bill of claim for the delivered uniform to the kindergarten.

How would it be applied if the kindergarten wishes to put an end to the contract and refuse to pay?