Incorrect debits

I pay my telkom bill via eft every single month. This month I paid in according to the statement I was emailed. My payments were not credited to my account and I was debited in the approximate amount of R600. This is unacceptable. I actually did 2 payments and it was never credited against my account. Telkom, I have been a loyal customer for over 10 years and is it right and treat customers fairly. I expect this to be resolved ASAP. Waiting patiently.