As merlin says - take that payment book to the court fines office, along with this letter, and show them.
Meantime, do not allow any bailiffs over the doorstep and keep your house well locked up. Until they've been allowed in to record what you have, they are not allowed to break in, whatever they may tell you or whatever they may threaten. If they claim to have a warrant, indeed if they show you one, insist on having the police present to verify it. Don't sign anything for them, either.