Costs incurred by an estate manager are relevant costs—
only to the extent that they are reasonably incurred, and
where they are incurred in the provision of services or the carrying out of works, only if the services or works are of a reasonable standard.
Where an estate management charge is payable before relevant costs are incurred—
no greater amount than is reasonable is so payable, and
after the costs have been incurred, any necessary adjustment must be made to the charge (by repayment, reduction of subsequent charges or otherwise).