(1) Subject to the following provisions of this section, any term of a contract implied by virtue of section 39 may be negatived or varied by an express term of the contract or by the course of dealing between the parties or by usage, if the usage be such as to bind both parties to the contract, except that where the recipient of the service deals as consumer it must be shown that the express term is fair and reasonable and has been specifically brought to his attention.

(2) An express term does not negative a term implied by this Part unless inconsistent therewith.

(3) The reference in subsection (1) to a term negativing or varying a term implied by virtue of section 39 is a reference to a term which purports to exclude or restrict, or has the effect of excluding or restricting, the operation of any provision of that section, or the exercise of a right conferred by any provision of that section, or any liability of the supplier for breach of a term implied by any provision of that section.

(4) Any reference in this section to a term of a contract includes a reference to a term which, although not contained in a contract, is incorporated in the contract by another term of the contract.

(5) Nothing in this section shall invalidate -

(a) [deleted]