Hi everyone, and happy Sunday

I need advice, one of my customers gave money (2K) to my subcontractor to buy lumber materials thinking that we are the same company, this sub didn’t refund the money nor provide the materials nor answer the phone or text. I told the customer you shouldn’t pay my worker or my sub since I did the contract and we did the scope according to the proposal, now the Thumbtack ask me to refund this 2k to the customer otherwise they will remove my account. Please advice