Being overcharged

[#1]

I recently moved home and was offered a 24 month contract at £6.99 p/m, a discount of £3, by the home move team rather than paying the cease fee and for a new line.
I received an email a few days ago stating that I would be charged £9.99 and immediately called the billing team to query the overcharge and was assured by the rep that, although the email stated £9.99, the £3 discount was being applied to the direct debit and only £6.99 would be taken from my account.
I have today checked my bank account and have been charged the full £9.99 so have clearly been lied to.
Can someone please ensure that the overcharge is refunded asap and that all future charges are for the correct amount.

[#2]

Let me look in to this, I don't think you would have been lied to it's more likely just a mistake but I'll post back shortly.

[#3]

I've corrected the issues and refunded the £3 back to you.
In summary, when the new discounts were added these were put on top of your previous discounts instead of replacing them. Unfortunately this meant that the total discount was more than your subscription and our billing system doesn't know what to do with this so just ignores all the discounts.
Sorry for the problems but it should be sorted now for you.