Debit order choas.

I was debited my right amount of R499 on December 8th. No problem. January comes and they debit my account R998. 4 WhatsApp conversations. Each agent at there wits ends to trying and failing toexplain what's going on with my debit orders. All my accounts up to date. 2 tickets subsequently ignored. No feed back. Got a call yesterday. Couldn't hear person on the other end. Presume it was supersonic. No call back. Then got involved with someone at head office who asked for bank statement. Statement was duly sent. My inbox still remains empty. Did try to phone direct 4 or 5 times. Says network is congested. Got a call back which I had initiated earlier this afternoon. Very pleasant lady informs that billing office is closed. Try again tomorrow she says. What I really want explained to me is who gives supersonic the right to debit more than the signed agreed to amount. Even if it turns out to be a valid reason , they should have communicated this to me in writing. Very scandalous business etiquette, in simple terms, bad business practice.