Overcharged again third month running

After a terrible start to a renewal online offer that was only resolved by the intervention of a forum representative, I have been over charged again this month, this is despite contacting virgin media last month, recieving an apology and them acknowledging I had been incorrectly overcharged and receiving assurance that it would be resolved this month. I have the screenshots of the conversation to support this and happy to provide them. I would like to raise a formal complaint regarding this, would like someone to actually resolve this and intend to take this to the ombudsman now as I have been left with no other option. A terrible experience throughout and I am being overcharged every month.