Problems with garage

Does anyone know who the the official body is to contact about a dispute with a garage and the work they did

Hi Sheila, we took our car last July to the village garage to have a temperature gauge fitted and they told us the cars computer wanted replacing so we went for it paying in total over 2000€ - recently the car failed its MOT on emissions so we took it to the opel dealer who told us that the work last done had been done wrong and we should go back to the garage that did it, one of the things they did was to disconnect a warning light to make out they had put it right, we went to the garage and the mechanic agreed something wasn't right but we would have to speak to the boss who was the woman who worked in the office part time, a friend who speaks French called this morning and was told she would call back, she hasn't so wondered if there was an ombudsman that deals with these things, Regards Roz

Hi Roz. Perhaps some more information about the situation???