It was great at first, now they are not doing well

It was great at first, now they are not doing well. I never skip payment, now i payed double for end of March and they don't want to refund me they told me that i was paying for April, since when i pay 1st week of every month for that month, they fixed the date because i always pay with eft so that they can see it before the debit date. Now when i told them they say my account is in arrears or i am paying for that month, if i ask for a manager they don't put me through. Please refund me i need to buy electricity with that money , we never agreed for 1st week i am paying for month end. Can a cell manager call me please