1999 Chrysler Sebring engine and transmission trouble!!

I took my 99 chrysler sebring to a mechanic in town and they fixed the transmission with something called a soleniod kit but they said that the engine was overheating because of a head gasket but if they replaced the bad one it would blow out the good one so they put in a new engine but they still wont let me have it because the lifters arent working right and they might need to get another engine and theres a water leak. what do lifters do???? its been a month since i gave them the car, does it normally take that long to replace an engine and fix a transmission??