Third member damage to rear axle

Just bought my 2008 Tacoma and I had a leak at rear axle, mechanic said it was third member damage and my rear axle had been sealed incorrectly before. It's costing me more than I hoped it would, I was just hoping for some information and literature on the subject. I'm knew to tacoma and just feel upset and boned by the used car dealership. Anything would help thank you guys

 

have you tried to get the dealership you bought it from do anything?

 

Yes. My warranty was engine and transmission only. They were absolutely no help to me.