Xbox goldlive promotion

My son mistakenly bought a £1 monthly discounted Gold Live instead of the yearly one for £26 on special offer on xmas morning thinking he was going to save money, I have discovered after first month it would cost £5.99 a month, obviously extrmely cross with
this decided to ring the. Xbox support line, the lady I spoke to was very helpful and advised that I could request a refund and then rebuy the correct discounted deal, she also gave me a different number which I could ring if I had any issues.

My account was reimbursed with my £1 however the said £26 deal did not return on my sons account, I have several calls and spoken to several different Operatives on the number given and nobody has been able to resolve the issue, all claiming they couldnt
change it as we could only claim the offer once (my point being my son was mislead into only buying the monthly for a £1 which was refunded and therefore havent actually used a deal) strangely the £1 deal is still available on the account !! The opperatives
wouldn't connect me with somebody who could assist.

Has anybody suffered the same or similar issues and had any joy in resolving? Any help or advise would be greatly received.

:)