Any provision -
(a) of the contractual scheme deed of an authorised contractual scheme, or
(b) in the case of an authorised contractual scheme which is a partnership scheme, of the contract under which the depositary of the scheme is appointed,
is void in so far as it would have the effect of exempting the operator or the depositary from liability for any failure to exercise due care and diligence in the discharge of its functions in respect of the scheme.