Pathetic customer service

This is directed to the Makro Ottery branch. I purchased a basic padlock, only to discover the key supp**** with the lock doesn't actually work with the lock. Over a week later I returned it to the Returns desk, explained my story, and the lady assisting me gladly accepted the return and issued me with a credit voucher. I then went to another area in the store as I was also looking to buy a Wahl hair clipper. I had to wait a further 15 mins to actually get the product I wanted as the store assistants were running around looking for a Wesley as he was the only person able to unlock the cabinet that housed the Wahl products. Eventually after another 10 mins in the checkout queue, I arrive to the counter, only for the cashier to experience difficulty in processing the credit voucher. She calls up the supervisor, who then asks me to go back to the Returns counter. When I arrive to the Returns counter once more, a different lady advises me that my credit voucher has been cancelled due to the fact that I returned the lock with the incorrect key!! That's precisely why I returned it in the first place! I ended up leaving the store without purchasing anything or resolving the initial matter as the staff cannot use any common sense and I did not have the time to wait to argue over a measly R89.00 lock. The service in this store is pathetic! Your staff could do with some basic problem-solving s****s.