Horrific Service when returning items

My husband went to buy an alternator yesterday, and we had the mechanic fit in the alternator in straight after the purchase, The alternator was faulty and made a loud noise, so we called Goldwagon Wynberg on the 27th Jan, only for them to tell us they cannot refund us until they are done checking whose fault is it for the alternator not working, which is a 2week process, we explained we require this part and when my husband purchased it no one advised in such a case what would happen, I am terribly unhappy about that service, we then needed to to buy another alternator as 2weeks is just too long!