Pathetic Service

In June i had changed my banking details which never got updated with Cell C on time. On the 12/07/21 i had made a payment of the arears amount including the interest which was R319.00. I then emailed them the proof of payment to *** & to ***. At the end of July they debited me double which they werent supposed to do. I had then contacted Cell C on the 5/8/21 & had spoken to Lerato, i phoned again 6/8/21 spoke to Nokwazi, i phoned again on the 10/8/21 & spoke to Angel i had then sent the proof of payment to her & she said that she was going to eacalate a case for a refund but yet no feedback was given. How many times do i need to phone and scream till i get an answer. I am not a happy client with them as they just dont care. I dont know what to do anymore.