I think I might be more concerned as to why suddenly are there fuses going so regularly, what is going on with the sockets if they did not do this before. You might find a temporary answer if you knew what they are plugging in when the fuse goes and encourage them not to. What do you think? At least until it can be investigated more thoroughly. Might be faulty equipment or overload from too many things on at the same time.
In my opinion they recently had a boiler fitted the old system was obviously removed. Some how they blew the 30a fuse so swapped the now redundant 15a fuse into the 30a carrier. When the high draw loads from the kitchen started to blow the 15a fuse as all the house sockets are on 1 fuse.