Sub contractor help

[399DPD]

I recently built a house and went through a reputable contractor in my area. The contractor hired the plumber, excavator and others to subcontract some of the work to build the house. The contractor used the bids from the subcontractors to fill out and sign a sworn construction statemtent through my bank. Midway through the project the excavator gave me a bill and the total was confirmed through the contractor. The bill was paid and when I asked the excavator how much work was left to do and the cost he gave me a "ballpark" estimate. The estimate was $3000 over the original estimate. I wanted to take care of the descrepency there but he gave me the "don't worry about it, we will take care of it in the end". I spoke to my contractor about this and he told me the same thing. Well as you can imagine the job is done now and based on my original estimate I should owe him just over $7000. He gave me a bill for over $14,000. I still owe the contractor about $3000 which I am holding until everything is figured out. When I confronted the excavator about this his story changes and he says "see this is what I figured would happen". When I talk to the contractor he says that the excavator is wrong and he will talk to him. Now, the contractor doesn't seem to want to be involved in this anymore as he keeps saying "speak to the excavator". Today I received a call from the excavator asking to be paid. I explained everything to him and he wants to meet to to explain the bill to me. I don't need an explanation, I don't think that I should pay this. There were small modifications to the original plan but no where near close to $7000 worth. I figure and talking with other construction personel that the changes should be around $1500. I am willing to pay the extra $1500. What should I do? Thank you very much in advance.