Unauthorized change of debit date

Absolutely **** service. My debit date has always been the 25th and upon trying to change it to the 1st and being given a message it would be the same debit date for this month and the new one from the next i was debited suddenly on the 20th and had my connection cut off, tried to contact support and I'm still waiting. I then paid the part payment and LOW AND BEHOLD I get another notification today that I'm now behind again and of course can not get hold of anyone ro explain to me why my debit date was changed without my permission. I'm appaled by the customer service.