Leaking oil drain plug

[OldCrank]

Had truck at dealer for brake work (again, see post in 2nd gen forum titled "2nd gen brake upgrade?"). Decided to have them go ahead and change the oil/filters since they had it and I had a laundry list of other projects to complete. Nice new oil leak came with it at no extra charge. Response? "Bad oil pan, that'll be 1200 mazoolas if you please. Wasn't our fault."
I pulled the drain plug to inspect the problem and found that the pan is indeed distorted. The pan has a threaded section inside the pan that is raised above the pan floor with four openings to allow complete drainage (sort of an upside down castle nut arrangement, which I've seen on other vehicles). Anyway, sure enough, there is just enough distortion at the points where the openings are located that oil gets out past the reach of the plug and seal. Obviously over-torqued and then some.
Yeah, I know, I should tapdance on the service managers desk and all that noise, but I want to fix it first, and put the hammer down after. I don't want them near it again, ever.
Gotta help me here guys. Does anyone make a drain plug with a larger diameter sealing area? Is this a common problem (there are no bulletins on it that I could find)? Another dealer said they never run across the issue. Other repair options? I replaced the seal, which made no difference, and have added a nylon washer that is a larger O.D. I'll know tomorrow whether that helped, but I need a fix that I can count on. Thanks in advance.
P.S. TDR is easily my favorite forum along with IATn (a technicians network).
BK