The answer is "maybe." If the mechanic gave you a warranty or otherwise guarateed the work, you may enforce that warranty or guaranty. In the absence of a warranty or guaranty, however, the mechanic is not liable simply becausue the problem persists--some problems are very hard, if not impossible, to eliminate, even for careful, highly qualified mechanics. The issue is whether the mechanic--1) Committed fraud--that is, he lied to you about something important, such as the nature of the problem, his qualifications, or even whether he was doing the work.2) Was unreasonably careless, or did the work much more sloppily or poorly or carelessly than would be expected of a reasonable mechanic (which includes using substandard parts).Basically, in the absence of a warranty or guaranty, you have to show that the mechanic actually did something wrong; if you feel you can show that, you would have a viable claim, and could potentially sue to recover the money you paid and/or for the cost to have someone else correct the problem.