Unprofessional service

I signed for my contract towards end April, according to them, the first debit order was supposed to go off end May. To my thinking, that's done. Just on the 20th June, my phone is locked and I need to contact the service provider. Upon my call, the consultant to assist also confirmed that there was no way the debit order bounced with insufficient fund. She put me on hold while checking few minutes later she indicated that my account is already handed over for collections. Tell me about it, just like that my name is being dragged into the mud ?. Why would one just intend to conclude that you are a bad payer if their system could do the actual job of debit. Now I am being pressured to pay the 500 Rands bill for May before my Sim get unblocked.