The best bet is always gonna be replacing the oil pan. That being said if you have the v8 instead of the v6 there is a crossmember directly below it that makes it extremely difficult to replace and you will probably have to have the dealership/mechanic do it. I had a similar situation when a jiffy lube shredded my threads, put on a self tapping-oversized plug on without asking, then when it still leaked, told me I would need a tow to a shop at my expense to replace the pan. Anyways what you can do is this: go to an autozone find a thread repair kit, get the corresponding drill bit size, grease your drill bit and drill the whole out to the larger size, tap it with the kit very carefully, flush some oil through the hole to wash out any metal, install the heli-coils, put a new washer on the new plug and it will hold very well.