Dissapointed from Telkom.

Very dissapointed with Telkom,have an contract with them where im paying a monthly of R368 till next year December 2021.So last month in April they wanted to Deducted R770 of which I dont know what is it for.Now i just got an sms from Telkom threatening Me that if I dont do the payment they will cancel the contract. I even tried contacting they're call centre but no response.Very sad and annoyed about this.