Telkom has the worst customer service

I had two contracts with Telkom mobile and wi-fi they stopped to debit my acc when I realized I phoned and notified them then they decided to debit me a lot of money to make up for months they never debited okay no problem now I have R531 which they need to pay back they even send an invoice for me to claim .When I try to contact them no one can assist and a telkom store can't they can only do a call back which they claim will be less than an hour but takes 3 days and you still can't get assisted all they can say is 'I'm sorry maam'the billing department never ever goes through.