I can't say this often enough, never entrust diagnosis and repair to a main dealer. Ok, take it to them if you must for service but take the report to an independent garage for a 2nd opinion and a none main dealer repair price is work is actually needed.
Pads and disc needing changing is probably the most common cause for complaint on here about dealerships, go elsewhere. I know it's too late this time but you are obviously not happy and not even convinced the work was necessary so approach it differently next time.
Check out this thread active today www.renaultkadjarforum.com/forum/wheels-tyres-brakes-suspension/515-brakes-wear.html?start=0