Contractor/partner claims over budget on rehab

[Jose Castillo]

So I did a flip with a contractor/partner and we had a budget for the rehab at 80K and he brought me a bunch of receipts with no PO regarding our subject property and is claiming that we went $40,000 over budget. He claims the rehab cost came out to 120K and now wants to collect the 40k at closing. He gave me some receipts but none have PO information of our property and which we both made it clear we should at the beginning. Any suggestions?