I have lost pressure to my taps upstairs there was a bit of pressure. The longer the hot water taps run the slower the water comes out

See: http://www.finehomebuilding.com/how-to/articles/improving-water-pressure.aspx
You are losing about 11-12 lbs. of pressure due to the water having to go upstairs, plus if the air has been absorbed in your air tank your pressure is already low. Try pressurizing the tank with about 60 lbs. of air and adjust the pressure up on the pressure switch. You should raise the pressure to between 60-80 lbs. to get good water flow. You could also have scale in the pipes that's slowing the flow of the water. You may have to replace some or all of the pipes. If you do replace the pipes make sure to put pipes that have enough diameter to carry enough water. In areas with hard water PVC pipes work best, and it's cheap.