Some fixed interest accounts pay the interest direct into a ,linked account on maturity date - did you have to set one up? They then "roll over" the capital sum into an easy access instant account unless you have told them otherwise. Not sure what AA do but their "parent" company,Birmingham Midshires, wrote to me a few weeks before maturity date recently with a selection of follow on options.
Last year a YBS account matured for me,I had forgotten about the interest going direct to my current acc. and had quite a shock when I looked at my online balance and found that I was several thousands better off (or so I thought for a short while!!)