Can someone more informed please let me know if you can have NR refund
vouchers added to an oyster PAYG.

I know LUL refunds go on as a voucher and then become 'cash' and therefore
don't expire, and I recently had a refund from Overground and the letter
stated I can have that added to an oyster at a L.O ticket office.

Having not tried this yet is it specifically an L.O ticket office, or can I
call into any LU office that I'm passing on a quite day ?


TIA.