What should i do if a dealer lied to me and the mechanic that fixed my car?

The dealer who sold me my car told the mechanic that he would pay for the repairs. when i went to get my car, the dealer told me that i could not have it until i paid him back. he never spoke with me about any of the repairs or how much repairs to my car would cost. he spoke with the mechanic but not me. what should i do?
Answer
Kikabeh you must report this a s a p to trading standards officer.if the dealer has a franchise inform the head office also.then tell the mechanic you are taking legal action which will implicate him as well due to his implicity .this situ smells bad .a word with a friendly police man may help to .best of luck .you could hint that you will name the dealer legally if need be .