Incompetence parts department

This could probably be solved in a better way but I tried.Very disappointed with there parts department supp**** wrong part to my customer and refused to give a refund. Customer supp**** sample of part and still wrong part was supp****. Its seems to me the parts salesmen only work from vin numbers and cant identify his products. Spoke to dealer principal and he cant help in any way only answer is they cant take the loss and he shifts the responsibility to a the complaints department he gives me a number to dail to lay a complaint I meen really now.A R5000 loss is a big loss for someone that earns a normal wage in this case a person with a part time job.