Well, fixing a bulge by digging a hole.
The floorers returned and having lifted the bulging Palio Clic, removed both the screeding underneath and the parquet in the offending section. The thinking was that the parquet had shifted causing the screeding to fragment and create the bulge.
Then the hole was filled with more screed.When this was dry the underlay was put on top. There was a delay for a day or two due to the bank holiday and the fact that more Palio Clic had to be ordered.
So now the floor is done and we just have to hope that no more bulges develop. If they do all the parquet will have to come up.