Dirty tricks

Had a data contract for short term with mtn as the product wasnt available with vodacom. Mtn overcharged me R1000. They confirm they can see the credit amount on my account. Now they want bank statements for each transaction where they overcharged me, even though they confirm they can see it on their side. A couple days later they closed the ticket with no explanation. Absolutely disgusting service. I'm appalled that they would request bank statements in the hope that I would forget about the entire thing. They could simply refund the overpayment just like any other company does. Never again using these clowns. Never had an issue with vodacom in 18 years.