This was my experience with HB.
I wasn't entitled to much after ds left nursery but I still paid ASC during term time.
I explained everything, gave them all information, yet every April they'd try and raise the amount a ridiculous amount. Every year I'd tell them it was wrong. Every year they'd overpay me for 2 months anyway (I put it aside).
Then send me a shitty letter about how I'd o been overpaid and basically hinting I had committed fraud, I could be questioned legally blah blah.
But ending my claim was difficult.
Until I sat in the council offices one day and refused to move until someone say with me, apologised, took back the overpaid money and ended my claim.