Wrongly billed.

2 times I scheduled a downgrade before my debit date so that on my debit date I should be downgraded and it never happened and in both occurencies I even called to ask why am I not downgraded and they said it is a system error. I have been made to pay for their system error. I want my money back because I did schedule a downgrade and on the 13/11/2015 I even caled for a downgrade and I was never downgraded and I am charged for that. 2months ago I was also billed for a decoder I don't have.