There were two brokers over the years.
The original broker processed all the claims and made the necessary payments. The original broker then sold its client database to a new broker. The new broker continued with the existing insurance company for nearly a year, and then transferred my colleagues business to a new insurance company.
This, I think, is where the problem lies. The broker must not have disclosed the previous claims to the new insurance company, and my colleague has no recollection of completing a new proposal form for the new insurer.