Aurora at Luna Park - Taylor Morrison

We had an issue and Taylor Morrison sent a company to open the wall to see the leak. Now they are saying it’s the next door neighbors responsibility but Taylor Morrison was the one that opened up the wall. They quickly came back for their tools but thought it was ok to keep our walls open. We waited for Taylor Morrison to let us know the findings and nothing until I had to open a case. I don’t understand the logic of they opened the wall how Taylor Morrison is not responsible for repairing it???