sometimes i have no water from hot tap on my bath i want to fix this perm' ?

sometimes i have no water from hot tap on my bath.we had our bathroom fitted by dolphin bathrooms[disaster] when they finished we had no pressure on the bath taps so they fitted a pump, now we have to run the sink taps until the bath starts.this is a pain and i would like to fix it permanent can anyone help?

gary
November 2009