ISP refuses to refund me

Webafrica debited me five times for one R209 transaction. For this, they had to refund me. Apart from this, they were also supposed to refund me R845 for another transaction. They keep insisting that they "processed my refund", although their own statement clearly shows only one refund was effected - which matches my bank statement details.

To resolve this, I have called them multiple times. Also, I have also sent them many, multiple e-mails including listing each of their debits from my account for every relevant day in May 2019, as well as adding up the cost of each service I use, telling them what my totals should have been, clearly showing them what they charged and debited me, and calculating the difference, which is the amount that they must refund me. Their answer is disappointingly to merely repeat that they have "processed my refund".

I don't know how to make the facts any clearer to them, or whether there are any people at their offices capable of assisting me. I am currently out of pocket for a significant amount and my ISP seems hell bent on ignoring the facts.

If you appreciate great service and communicating with helpful people, look elsewhere. I want to like them, but it is becoming increasingly difficult. My experience has been very disappointing and frustrating and I don't wish it on anyone.