Refusal to refund wrong fan belt sold to me 3x despite protest its wrong

I was sold a wrong fan belt for my Mercedes at your Silverlakes branch, three times despite telling them after the 2nd one, that my mechanic says it is small. the salespeople convinced me it the correct size and we took their word for it. The 1st one unravelled after a week, the 2nd after 2 weeks and the 3rd after 5 days. This has even affected the car's tensioner. The manager Cody, dismissed my complaint and blamed me. I told him I am going to report, he said go ahead without a care in front of other clients. This place is walking distance from my house and I trust Nalar parts and the reasonable proces. however I am now disappointed and may not buy there anymore.