No knows what they are doing

I usually request for a premature cancellation on contracts when its due for an upgrade or cancellation and the process always runs smoothly without any problems or issues, however in June I requested for my cancellation figures of which I received it and was informed that the total amount owed included June's debit order and it is evident on the quote. Payment was made and my contract cancelled however my debit order still went off on my account and when I enquired about everyone acted as if I was an idiot and kept on insisting that the debit order which went was indeed correct and that the quote excludes the current months payment, having to explain to the call centre agents like a toddler what I was told and what is reflected on quote the total payment included June's debit order, I was soon advised that it was a mistake on there behalf and i will be credited, yesterday upon enquiring i found myself in the same position having to explain one 3 times, i was then referred to the accounts department because they need to sort it funny the department who quoted me the quote is not at fault and i need to sort out there mess. I want this resolved today