1990 Acclaim Rocker arms keep comming off HELP!!!!!!!

Ok here goes..... I have a 1990 Plymouth Acclaim 4cyl it wont start so i took it to the shop the guy told me that the rocker arms were off and he put them back on . Well they are off again. He now told me I could replace the head and this would fix the problem, I would like some advice on this as i am a woman and it seems to me that he may just be taking me for my money he was suppose to do this already. well i was under the impression that he did anyway. if anyone knows why these are coming off please reply as i need my car for work. Thanks.. Darlene:banghead: