More cold showers!!!

[malks]

Our combi boiler broke, and ever since it was fixed (by way of a new thermostat apparently...) we have been unable to get a decent flow of hot water from the mixer shower or the bath. Other hot water taps are all working as before. When I turn the shower/bath to maximum temperature I can get a warm flow for about 30 seconds then it goes cold again and I have to turn the shower off for about 60 seconds before I can get a warm flow again. Also, if I run the hot bath tap slowly to keep the flow hot I've noticed that sometimes the water pressure drops off to a dribble, at which point the boiler thermostat will show the temperature in the boiler increase to very hot temperatures - if I now turn the tap on full extremely hot water will come out. Any ideas what the problem is??? Thanks.

[ChrisR]

Yes lots but you need to tell us the standard stuff.
What boiler is it, and how old?

Can you turn DOWN the temp on the boiler - may help the shower.