I am currently having a nightmare trying to transfer a balance off an AA credit card!
I tried Capital one first and they said they were unable to transfer a balance off an AA card as the bin range was not on their system. I therefore agreed to close the card and have my credit history reset.
I then took a CC out with HSBC and they initially tried transferring the balance under a AA MBNA mastercard and it failed. It turns out that in 2015 AA changed to Bank of Ireland so they tried it again with the Acc Number and Sort code they have stored on the system for AA BOI and again it failed. I then went back to AA and asked them to confirm the account details. These turn out to be Acc 9943016 (HSBC have this correctly) and Sort code 904616 (which HSBC have as something different). This issue has now been going on for 3 months and i am being charged a high level on interest on the AA card balance and can not get it transferred of through no fault of my own. Im fed up of being the go between in this issue when surely if HSBC spoke to AA and confirmed the details it would resolve the issue.
PS Word of warning to anyone looking at AA Credit cards, be very careful as both Card providers i have tried to get the AA balance transferred over to have not been able to do it!