Complain about refund for the undelivered order

My name is Seth. I ordered a seal for a nissan np300 hardbody at BB motors in Tzaneen. I was serviced by a guy called Bertie. He promised to call me for collection as soon as the seal arrives. I waited for about three days and he said he has not received it yet. The answer was still the same after about ten days. I decided to request myoney back since the part was not delivered. He requested that I give him the copy of the invoice,the id and bank confirmation,which I did. I waited,and after about three days he told me they are busy processing my refund. Since the twelfth of July up to date the 25th I have been given empty promises by this Bertie guy for my little refund of R747,87 which Tzaneen BB motors,a company that is making millions, is failing to refund me.