Know Your rights as a customer

I ordered spares for a cmc vehicle from CCE Holding, Spoke to the lady obtained a quotation. Quoted my client, got the go-ahead. I paid this company and the got the courier company to collect the part and bring it to durban for only to see that 1 of the 2 mechanisms is incorrect.

Called back spoke to the lady, took pictures and emailed it to her to show the incorrect part. I got no response from her for 3 days contacted her to follow up. SHE TOLD ME TO COURIER IT BACK TO HER.

she received the parcel, calls me and tells me that shes not paying the couriers i should paying (For something that they incorrectly supp****). I spoke to her boss a so called "businessman" tells me i should have told them to collect the incorrect part.

Why should i bare the cost of courier for something that wasn't my fault. Such poor business ethics and customer services.