Thanks for the replies folks - appreciated. I'm not going to file a complaint; ATC have their job to do just as we have ours and I'm always very respectful of that. (Plus, I'm pretty new in the LHS and don't want to kick up an unnecessary stink!) I am just interested in finding out if I understood what happened correctly and if there was some SOP in CFMU that I wasn't aware of. I was a little taken aback by the notion that you can be given a proportionally worse delay simply for the late notification (about which we could do very little) but if that's the rules, so be it. At least I'll know for next time.
I'll run it by the base captain as you suggest, SN; that's usually my first port of call.