回复：如果你朋友会做人，也许人家会免费送你一个盖，车子会无事，省心省钱

Actually I think the one thing he could have done is to inspect the cap after the 70k repair. He was already told that the cap needs to be replaced. 

It's very likely that the mechanic can't just give him a new cap because the mechanic screwed up.