I've been screwed by MBNA..Help!

So a couple of weeks ago I was browsing through the balance transfer cards and saw I had a 95% chance to be accepted for both a MBNA and Barclaycard. I already had a MBNA money transfer card with a £5k balance but I figured they will probably accept me for a second card since it was such a high percentage and I took the chance .

I got instantly approved for the Barclaycard with a credit limit of just over £15k but with MBNA, they tell me I will be 'contacted soon about my application'. A few days later I requested a balance transfer from my Barclaycard to my already existing MBNA money transfer card. I messed up the maths and ended up having a positive balance of slightly over 10k on the MBNA card. Immediately MBNA suspend my account .

I then call MBNA to find out whats going on and after getting transferred through to several different people they tell me that not only has my application for my second account been declined but my existing account I have with them has been suspended indefinitely. After assessing the situation I figured to limit the damage I need to transfer the 10k into my bank account , so I call back a few days later and the person assures me all I need to do is wait another 5 days then request a credit balance refund. So I wait the 5 days then call but they then tell that it hasn't been cleared yet and I have to wait a couple more days, After calling again, a different person tells me that I now need to confirm some information about my credit file and that I should call back in a couple more days, so again after waiting I call back, this time the person who answers has no recollection of my previous calls and tell me to call the fraud department who will be able to answer all my questions.

When I get round to calling the fraud department the guy who answered turned out to be no help whatsoever, he tells me he has no idea how long my account will be under investigation for and he's not at liberty to discuss anything with me, and just to rub salt in the wounds he tells that there's no point in further contacting MBNA.

Now if MBNA no longer want me as a customer then I understand, but the problem is I have 10k+ just sitting there in the MBNA account, and to make matters worse I have to pay a minimum payment of £300 a month to Barcalycard for the balance transfer I made. I surely cannot go on like this for much longer, MBNA must think I'm trying to commit fraud. What should I do? ask MBNA to return payment back to Barclaycard? call MBNA and try to explain exactly what happened to speed up the investigation? I feel quite helpless right now . There must be something I can do.

TL;DR I have 10k sitting in an MBNA account which I am paying £300/m for and MBNA have placed my account under investigation and told me not to contact them.