Thanks for the reply. You assume correctly in that we missed the CTOT+10 window (or rather, would have done had we bothered to try.)
I know there's nothing unusual in getting a slot an hour later than the missed one. My question arose specifically because I stayed on the telephone to our ops controller while she was re-filing for the new slot time and she actually used the words "you've been given a late update penalty" as if she was reading it off a computer screen.