Sticking notes on T.Aldous' door is the tried-and-trusted way of keeping the service ticking over in the man's absence. It's a magical property best left unquestioned because it works perfectly.
I've just heard somebody singing (to the "Sheila's Wheels" jingle):
"If you don't want to be a whore
Stick a note on T.Aldous' door."
Lending have taken advantage of the situation. They told Seth to go missing for a while and then rang Frog up to say that a customer was stuck in the lavatory and seemed to be having breathing problems. They did an excellent job of keeping straight faces as Frog tried to check that the "customer's" obvious moans of pleasure weren't some sort of seizure.