Guarantees not worth the paper

At present we are working on a property with a basement affected by a failed cementitious tanking system. The homeowner had a guarantee signed by the contractor that installed the waterproofing, and also the product manufacturer/supplier - great right? Well.. no! The contractor is no longer in business, and when the homeowner phoned the manufacturer, they said 'we don't guarantee workmanship'. Very clever that they knew it was a workmanship issue from a phonecall (without inspecting), but regardless, the homeowner literally has a guarantee not worth the paper it is printed on. So, in opening up and removing the friable tanking, this is part of what we found:

‍