Renualt Clio 1.2 Grande 2000 model ?

My Renault Clio makes a rattling/knocking noise when on a hill trying to do clutch control, this has only happended since I took my car in for a service /mot at a local garage, the garage is not at all helpful, I paid 300.00 cash, the garagehad even left the filter cap unscrewed!.
Prior to the service I have not had any problems with the clio. The garage said they replaced the front and back brakes but I am not even sure if they actually replaced them. I beleived they have ripped me off! Can anyone tell me what the noise is....