hot water problems

hi all please help,

i have a mersey super hot water boiler and the pilot light keeps going out, i replaced the thermo couple today and it appears to stay on a bit longer but if i run a bath/shower or fill the kitchen sink up it goes out after the hot water has run, you can actually hear it click itself off so you have to re-ignite the pilot light to get more hot water, do i need a new heat stat?

It does not have a "heat stat".

The T/C is a safety device and anyone working on a gas appliance must be competent and that would usually mean CORGi registered.

These are rather trickey appliances even for a CORGI engineer!

Tony