No pressure in bathroom hot tap - pump failed and replaced

hmm, sounds like 2 separate issues to me, as the pump and header tank are on a different system to the hot water, maybe a bit of debris has found its way into the hot water pipe near the tap, if it has then it might be trapped just below the tap cos the diameter of the pipe is reduced where the tap connector is, the only remedy is to turn the hot water off and cut the pipe under the bath about 6"down from the tap and remove the tap connector, if you are lucky the blockage will be visible, if not get a bin bag and a bucket, tie wrap or tape the open end of the bin bag around the open end of the pipe and put the closed end of the bag in the bucket, turn the water back on for 5 seconds and off again, the blockage should blow out into the bag and as for the header tank filling, maybe check the pump is pumping in the right direction if so try turning it down, there is usually a 3 speed dial on the side, if its on 3 turn this down to number 2 and see if the tank still fills...