No reply from ADT they just bullying me to add more cost on my acount and dont return calls

I have been trying to solve a billing isue for 3 years now and inpossible to solve this issue. In the meantime they just keep on adding intrest as they promise they will phone me back. But this never happens and then another month past more intrest is addit. They also kept a debit order going thru a acount thathey were told isnt active anymore and cost me a fortune on returned bank cost.