You can not transfer balances from one MBNA card to another one. Yes you can get another MBNA but you can't transfer balances from MBNA to that.
What you can do is take a balance transfer amount to your current account (they currently have a promotion of 0% on it until February).
Than after a couple of days you pay the money back to your MBNA card and as they always apply the payment to outstanding balance with the higher % apr first you have an advantage.
Check your T&C in respect of fees/offers/payment allocation but generally this is possible.