Can I sue my mechanic if he has had my car for 4 months and has not fixed it and I have received no receipts of anything?

My question is this, I bought a car last October 2012 and unfortunately my car was malfunctioning and had some mechanical problems the seller did not mention. I did not find out about these problems until a month later on November 22 when the engine light began popping up. A friend of my father recommended him a mechanic who we could take our car to, this mechanic is his friend. He came by to our home to check out the car and we paid him around $100. He took the car and changed a sensor. He showed my father the receipts of everything he had done to the car, but when my father was bringing the car home the engine light came on again, he took the car back and the mechanic checked the engine more thoroughly, he then told my father there were more major problems in the engine. He told us the car's gas tank or motor had sugar or soda residue. The oil pump had to be replaced as well as the turbo, and some other parts of the engine had to be cleaned. My father gave him a total of $1,400 throughout 2 months and handed us no receipts. He took over three months giving us excuses of why he had not finished fixing our car. He also repeatedly informed us parts we had already paid him to buy. We are very frustrated because it has been 4 months since I bought this car, and this mechanic has not even done the minimal work on my car the whole engine is parted and on top of it all the same friend who recommended my father of this mechanic told my father that the mechanic had personally told him he had ruined our engine. He was supposed to take it to a professional place to get a head gasket I believe re-modified and he tried doing it himself and apparently ruined it. My father confronted him about this incident and he denied the whole thing. He now claims there are other things he must fix and that he had lost some of the parts. My father has gone to his shop many times, but sees no progress at all. My father saw evidence of him working on other cars, and has left ours there with.