Deducting more than what was arranged

We've decides to be part of Virgin Active in January. There they told us that my 2 boys will be free for a year. only to find out now that 'Im paying for them. I've phoned head office they said I must phone the branch in Three Rivers to sort it out. So I did phone them. I even went there myself only to hear that the promo ended the 14th of January and we signed up the 17th. So I told them that its not my problem We were told on sign up that my boys are free for the first year. Now all of a sudden its different stories. If i knew I had to pay for my children I wouldn't have signed them up and I wouldn't have signed myself up. They can't say one thing and do another. So Im going to stop my debit orders on Virgin Active and they can kiss my ass for the money as they are the ones that are taking extra monies that was not agreed on. This is totally bad from their side and I will never ever suggest them to anyone as they are not keeping to what is said. And totally doing something else.