From the Landlord & Tenant Act 1985 - not certain if relevant after you have moved out but it might be worth saying that you consider he is in breach of s19.
19.—Limitation of service charges: reasonableness.
(1) Relevant costs shall be taken into account in determining the amount of a service charge payable for a period—
(
a) only to the extent that they are reasonably incurred, and
(
b) where they are incurred on the provision of services or the carrying out of works, only if the services or works are of a reasonable standard;
and the amount payable shall be limited accordingly.
(2) Where a service charge is payable before the relevant costs are incurred, no greater amount than is reasonable is so payable, and after the relevant costs have been incurred any necessary adjustment shall be made by repayment, reduction or subsequent charges or otherwise.
(3) An agreement by the tenant of a flat (other than an arbitration agreement within the meaning of section 32 of the Arbitration Act 1950
[4]) is void in so far as it purports to provide for a determination in a particular manner, or on particular evidence, of any question—
(
a) whether costs incurred for services, repairs, maintenance, insurance or management were reasonably incurred,
(
b) whether services or works for which costs were incurred are of a reasonable standard, or
(
c) whether an amount payable before costs are incurred is reasonable.
(4) A county court may make a declaration—
(
a) that any such costs were or were not reasonably incurred,
(
b) that any such services or works are or are not of a reasonable standard, or
(
c) that any such amount is or is not reasonable, notwithstanding that no other relief is sought in the proceedings.
20.—Limitation of service charges: estimates and consultation.
(1) Where relevant costs incurred on the carrying out of works on a building exceed the limit specified in subsection (2), the excess shall not be taken into account in determining the amount of a service charge unless—
(
a) the requirements of subsection (3) as to estimates and consultation have been complied with, or
(
b) those requirements have been dispensed with by the court in accordance with subsection (5);
and the amount payable shall be limited accordingly.
(2) The limit is whichever is the greater of—
(
a) £25, or such other amount as may be prescribed by order of the Secretary of State, multiplied by the number of flats in the building, or
(
b) £500, or such other amount as may be so prescribed.
(3) The requirements are:-
(
a) At least two estimates for the works shall be obtained, one of them from a person wholly unconnected with the landlord.
(
b) A notice accompanied by a copy of the estimates shall be given to each of the tenants concerned or shall be displayed in the buildings so as to be likely to come to the notice of all those tenants; and, if there is a recognised tenants' association for the building, the notice and copy of the estimates shall also be given to the secretary of the association.
(
c) The notice shall describe the works to be carried out and invite observations on them and on the estimates and shall state the name and the address in the United Kingdom of the person to whom the observations may be sent and the date by which they are to be received.
(
d) The date stated in the notice shall not be earlier than one month after the date on which the notice is given or displayed as required by paragraph (
b).
(
e) The landlord shall have regard to any observations received in pursuance of the notice; and unless the works are urgently required they shall not be begun earlier than the date specified in the notice.
(4) For the purposes of subsection (3) the tenants concerned are all the landlord's tenants of flats in the building by whom a service charge is payable to which the costs of the proposed works are relevant.
(5) In proceedings relating to a service charge the court may, if satisfied that the landlord acted reasonably, dispense with all or any of the requirements of subsection (3).
(6) An order under this section—
(
a) may make different provision with respect to different cases or descriptions of case, including different provision for different areas, and
(
b) shall be made by statutory instrument which shall be subject to annulment in pursuance of a resolution of either House of Parliament.