Telkom owes me R2000

Telkom debited R3000,00 on the 22/12/2023 from my account 6 day's after I paid R2000,00 into nudebt to pay for my contact. I have been calling and sending them emails to get a refund or for them to credit my account without any luck. Now they blocked my internet service and say that I have to pay about R600 for them to restore my internet access. My question to them was why do I have to pay them if they have my R2000 that they did not credit me I am not getting any response from them.