MTN Will not refund me my money after returning charger that is not working!!

Very bad service I received at Mtn in Bronkhorstspruit. I bought a type c charger on the 13th July 2021,when I got home it was not working. I returned it the next day. They took my banking details and said I would receive my refund in 5 days. It has been 2 months since iv been waiting for my refund, despite countless times going to the store! They do not even want to give me details of who I can talk to concerning my refund!