Hole underneath laminate flooring

Hi all,
I had a kitchen-diner knockthrough done at the end of last year. There was a radiator on the wall which came out, so naturally, this came out too, leaving a trench along the floor where the pipes were. This was filled in by the builder (which, it turns out, did a pretty bad job of things and cut a lot of corners...). I then hired a floor person to latex the floor and lay laminate. He said the builders did a bad job of filling in the trench, so he re-did it and waited until it was dry. He asked if I'd like the laminate gluing down and I said yes (in hinsight, bad decision!). Well, where part of the trench was has now gone soft and it feels like there's a hole underneath the laminate. Not a colossal hole but it's there and I worry the more we tread on it, the thinner the laminate will become until it finally rips. It's an expensive laminate (well, £400) but I'm dreading the only solutions being (a) drill a hole into the laminate to fill in the hole or (b) rip the entire laminate up, fill in the hole and re-lay - I imagine this would destroy the laminate, being as it's glued down?


Any suggests are very welcome. Someone thought the builder might now have capped a pipe off properly and the filler might be disintegrating if there's a small leak?


Thank you in advance!