Barclaycard balance transfer put me over my limit

csh_2

I wanted to do a balance transfer online but had issues logging in so phoned the internet helpline as advised.
They sorted whatever the problem was and said they could put my balance transfer through for me on the phone.
I asked how much i could transfer and they said X amount, it seemed high so i asked again and they repeated it.
I opted to transfer less than that and it all went through.
The day after i logged into internet and seen i was over my limit due to the balance transfer.
I don't undertsand how this has happened as i though you could only transfer up to 90% of your available credit.
I messaged them and they have said they have cancelled all my promotional rates (i only use this card for lifetime transfer offers) and have charged me an over the limit fee.
I have messaged back saying I am not happy as i feel their error has caused me financial difficulty.
Where do i stand on getting a resolution? I ideally want them to raise my limit to cover the balance transfer they authorised and reinstate the promotion rate.
Just looking for some general thoughts really