When we signed our contract and the price for the contract we had seven pages of architectural drawings and a line by line item contract that was almost 30 pages long. You would think that these items would leave very little wiggle room during the final invoicing part of the process. Oh how wrong you would be. Fortunately for me, I spent basically a year at work doing nothing but arguing over finer points in billing invoices and pretty much knew the process.
Step 1: Go through the charges with a fine tooth comb and compare everything they are charging you to the contract. This step yielded about $3,800 worth of disputed items. The largest was an argument over how much the contractor paid for the tub. Colleen sent them a very explicit email stating how much the tub cost both at an online retailer, or if thy weren't comfortable with that, then the price at Lowes. They chose to get the tub elsewhere and overpaid by almost $2000 and passed those 'savings' on to us. Most of the remainder of disputed stuff was for not reducing the amount we owed for items on our allowance sheet which we purchased ourselves (after the tub incident, we preferred to make purchases when possible). Everything from bathroom mirrors to overhead lights added up to quite a bit.
Step 2: Have a meeting. Experience has taught me that you need to have a meeting with all interested parties on your home turf and talk in generalities about what's wrong. If you get too specific at this stage, they will get defensive and try to hone in on one dispute, tell you why you shouldn't be disputing that item, and then assume all the rest of the disputes are wrong because they disagree with that one piece. Colleen and I had a great meeting with our Project Manager and our Architect in our new dining area. They listened attentively, didn't get defensive, and when it was all over, I sent them the detailed workup of every cent I wanted back.
Step 3: Be prepared to bargain. In Step 1, you really want to ask for the moon. That way, they can counteroffer to save face and you still end up getting most of what you wanted in the first place. Fortunately for Colleen and me, the only thing they didn't really go for was some vague he said/she said items that I didn't really think would fly anyway. They gave us pretty much everything I felt we were owed.
Step 4: Pay the invoice. Unfortunately, the approved final invoice ended up coming at pretty much the exact time that Colleen was paying for the second half of the Beach Week trip (we split a house with about 16 friends so paying for half of it is a big check). It also came just before we got our tax refund. Fortunately, we were able to shuffle enough cash around to get everything paid, but never forget the importance of cash flow.
So nearly 11 months to the day after giving them the first payment, we gave them the last. Now for all the stuff Colleen and I have to still do . . .