"No, we can't fix it, it's water damage."Here's a tip for those occasions.
Section 15(1)(b) of the Consumer Protection Regulations 2001 say that a supplier
"shall fail to meet minimum standards of performance if" ... "the supplier quotes scientific or technical data in support of a claim unless the data can be readily substantiated". (My emphasis)So next time they say this, remind them of The Law and demand a full technical report, substantiating their claims.