Think it's up to you to ring them otherwise they knock it off next years.
Rang them up a few years ago about an unrelated matter, after I had got the answers I
needed the woman said "by the way sir do you want your over payment leaving on account
or we can send you a cheque"
I didn't know I had overpayed to the tune of £500 but told them to send the cheque.
To this day I still think they made a mistake but I wouldn't have known if I hadn't rung
them with a query.
John