I don't believe VM, I have been trying to get my bills sorted for the past few months.
I got 3 £2 Tickles and my bill went up £6, on checking back through my previous bills I had been consistently overcharged £3 each month, Retentions sorted it all out with Credits and told me that the 100 Meg Broadband was being reduced to £25.50 from the beginning of April, which I already knew about.
Today I get notice of my next bill and they have charged me £27.25 for 100 Meg. Rang Billing and explained the problem whereupon I was told that £27.25 was correct, I guided Rasheed to the Broadband Prices page on the website and showed him that it was listed at £25.50, “that's for new customers” he said, “I pay the same as new customers” I told him, “not a penny more”, he goes off to talk to his Supervisor, comes back and says I am right and that he has changed my account accordingly.
A word of advice,
Check your VM bills all the time.