End result: they don't know why they're £19 down, but they decided that I did put in £50 and so credited me that, plus an extra fiver as interest and a way of them apologising. I was chuffed by this so went down the road and bought them a small box of chocolates to say thanks.
So, now I've got that £50 back in the account, I'm gonna ensure I spend it. After all, this was money I'd effectively lost so I'm gonna treat myself and random people good and proper.
Another excellent thing happened too! I got myself a wonderful t-shirt from Holly, with Specter on the front. I will show off pictures of this in the future, for it is an excellent t-shirt. I just hope it doesn't shrink too much after the first wash.
I have a mild headache. I may have a rest later on.