wrong parts supp**** by salesmen

I needed to buy spares and body panels for Mercedes xd250 i took in the bumper for the salesmen tapelo to order me the correct parts to avoid delays with incorrect parts, parts arrived late the fender provided was damaged we came to an arrangement and got it at a better price that was sorted when it was time to fit the washer nozzles and washer on the bumper it was the wrong side supp**** i contacted the salesmen tapelo and he advised me there will be no returns it not his fault now how can it be my fault if i took the bumper to him to supply the parts i did not tell him this part or that part i took the damaged parts over him and his other salesmen had a look and quoted me i then gave them the quote number and paid for these spares the attitude i get is not even funny he said his manager vis also cant help me now that the problem was not made by my mistake i sit with these incorrect parts which then i sourced from a different supplier they services is pathetic motus group please advise how this can be resolved my contact number is 0817278746