Mechanics gone bad

These people came to fetch my car and i paid upfront before the started to work on my car,they were supposed to replace bent valves and polish and clean my head..i got my car back two weeks later in a worse condition,making a loud noise,upon inspection we noticed that only the valves was deplaced,nothing was done on the head...they ignore my phone calls and messages,please people be carefull of these guys situated in sannie street pretoria gardens.