Help!! No hot water!

Hi,
I have a kingfisher gas boiler, and i have an indirect cylinder tank (i think it is anyway as i have 2 storage tanks in my loft) i sometimes only just switch the hot water on as its been too hot for the central heating. It was not until i ran a bath that i realised i have no hot water, its just luke warm. I switched on the central heating and the radiators are hot and working, the boiler is on too. Some of the pipes are hot coming out of the cylinder. I just wondered if anyone had any ideas of what it could be.
Many thanks
Debbie

Its probably one of those complicated bits like a motorised valve box has failed.

Moving the little lever on the side and latching it may give you a temporary improvement.

Tony

Oh that does sound complicated! I need a plumber then by the sounds of it.

Than you for the reply, its very much appreciated.
Debbie