Recently, a new toilet is installed in my house. The cistern is the new fluidmaster push button. The water is from the cold water tank in the loft. The toilet is on the ground floor. The water filling process is very very slow. It takes 25 mints to fill the 3/4 cistern. However, when tried to using the main supply, it filles in 2 mints. Obviously, the water pressure is the key issue. The toilet is the Wickes "toilet to go". It is cheap. Wickes said thousands have been sold but no one complained about the filling water problem. Wickes also said there is no requirement for the water pressure. What could be wrong?