What Actually Happened
I was introduced to a mechanic by a neighbor to help me increase the speed of my car uphill with a guess that it could be a geer problem. When I got there he test drove it and said it has no geer problem but he can give a fix. I waited for the whole day, towards evening he said I should drop the car with him till 11am next day, I did and called by 11am the next day he told me his working on my car that he will call me when it is ready. I told him my car is full tank fueled. I felt not comfortable and went to his workshop but was told he is not around. I called him to tell him I am in his workshop, he replied that he has taken it to someone else workshop to fix it that he will call me when it ready. I waited the second day and left his workshop by 6pm. He called me the third day morning that the motor is ready so I rushed for it. He told me that he has fixed it and test drove with me but we couldn't get uphill road to verify his claim didn't notice any change in the speed. He charged me 10k, I gave him 5k and told him if I can get the change I need in the speed uphill I will balance up I checked my fuel gage and it was half tank . Instead of the expected change the motor engine increases in heat. I complained to him he said it is normal. When I was not comfortable with the heat the vehicle produced I bent down under to check what could be wrong then I saw a portion of the vehicle silencer has been cut and replaced with an iron pipe. I called people to it and I was told that the mechanic has gone away with my vehicle indomie. I called his intention to that and he said I should come for it. He gave it to me but I want to collect my 5k and my 3k value of my half tank. I called him to tell him to refund me and he said he traveled, that when he returns he will let me know. He has not called me since then and I have decided not to call so it won't turn to child play.
What I Want
I want a draft of letter to him introducing yourself as my lawyer and writing him on my behalf to refund the 5k and 3k value for my half tank

The amount you'll pay a Lawyer is more than the amount you want to recover

Lawyer on how much Most of the mechanics are fools, thank God he didn't charge more than that.

U mean he removed the catalyst converter