I have recently had the garden done up using porcelain paving and artificial grass. The problem I have is that the grouting used (wet mix) by the installer did not dry in certain areas. Now to cut a long story short we were told by the manufacturer that we had to allow 28 days to fully dry so we did but still no luck and the manufacturer has not come back with a solution. In the installers defence he took it on the chin and came round and removed all the grout and replaced it with a different product but again its doesn't appear to be drying in certain parts. Any ideas as I'm not sure what to do next.