Is it fair?

It is my first time using Telkom on contract and my experience has rather been devastating, and it has only been 2 months, the agreement on the contract specifically says the the debit order will be on 25th of each month, but they failed to take their own money, which reflected their incompetence. I did not receive any sort of warning, nor an sms or a phone during the past months of my overdue account, now I have to pay twice the premium plus this months premuim and interest. I was placed on hold today for more than 15 minutes during my call with the customer care line. What I am trying to understand is who took upon a decision to go against the agreement on the contract which clearly states that the debit is on 25th and not the 5th.