I know lots of people that have had massive hassles returning their leased cars. It is not "free driving." You cannot turn a car back in with worn brakes, dead itres, cracked windscreen, etc. Then, they work hard to get you on the hook for everything so that they can just turn around and sell it. "Normal wear and tear?" What is that?
In James' case, they are being WAY too picky. Is the residual that high that it was to your benefit to give it back instead of selling it?
As for the leasing company actually using your dough to fix stuff, no way. A friend of mine in the car biz buys lease returns for resale, and he ALWAYS has to put brakes, tires, windscreen, etc. on them. The leasing company pockets the money and accepts a lower auction price. But, they often charge an outrageous amount for repairs, and I bet they come out ahead.