67If there is a breach of warranty by the seller, or if the buyer elects, or is compelled, to treat any breach of a condition on the part of the seller as a breach of warranty, the buyer is not by reason only of the breach of warranty entitled to reject the goods, but the buyer may
(a)
set up against the seller the breach of warranty in diminution or extinction of the price, or
(b)
maintain an action against the seller for damages for the breach of warranty.