Billing dispute for a faulty new phone

After cancelling my contract for a phone which became faulty after one day of use, I got debited twice and i haven't even received my re-fund. I will never take a contract again with telkom. You've given me 3 months of hell and you keep debiting me for something i don't even have and when i reverse the debit order you want to blacklist me but you not resolving my billing dispute.

I hate Telkom. You're a ****.