Caveat renewal delays at registry

I thought that as long as you got your application to extend in before the expiry date ( did a paper one) you would be protected. However I was wrong. We got application to extend in on date it expired 9th via recorded delivery or whatever they now call it.
The probate registry did not deal with it until 22nd, and on 16th they issued a grant. What are everyone’s views? They say we should have got it in in good time, but the only reference I can see to this is them saying you can make an appointment with a registry if it is urgent. Of course this won’t happen to me again, I will do it online, and luckily I am not sure if the outcome is not better for my client, but what is everyone’s views on this?