I am assuming that it is a typo that the agreement runs for minus 1 day, and is actually for 12 months. So the amount payable equals £33.33 per month, a not unreasonable amount for you to retain their services for.
Would you rather have it that every bill had 5% or whatever added? Much more transparent to pay a known fee so the maintenance organisation can cover the costs of the new legislation.
I do think that they should have discussed this with you in advance, so you knew what it covered and why it was being charged.