Disappointed. Poor service

I have been a loyal customer. Paid my account every month on time. This month I had to change debit order date. Date was changed successfully. Nobody has told us that we need to pay the extra days. Called in asking if they can not deduct the minus on the new date. Manager was going to call me uptil now no phone call from manager and services is disconnected. I feel frustrated as that is poor customer service for a loyal customer. Paid months and not even grace for 10 days. Disappointed in the service!