Unauthorised payments

i am beyond desperate, a young child has used my bank card to buy points - 148 purchases in 11 days. Microsoft say i cannot have a refund even though it was unauthorised, they hsve paid back 1 of thr 148 and say i can only claim for a refund once in 365
days, even though these are all part of the same unauthorised event.

The support staff start by saying they will get it sorted then after 30 mins say they cant help as it is up to the recund team. You cannot speak to the refund team, you have to e mail but they dont answer the question they just give a standard policy answer.
I have been told i cannot complain about the whole process instead i have to put it on here. My bank have told me microsoft are liable and have told me speak to the complaints dept (there isnt one).

I have lost a lot of money and am in a desperate situation, please will somebody help.

:)