Shower varying temp and pressure

[trancer]

Our shower is driving me mad. During the course of a shower the temperature keeps changing and the water pressure drops, then comes back again (sometimes). Other times it's fine! Any ideas what it could be? It does it when there is no one else at home and no other appliances on, I did think it might be because the washing machine was on, but no.

It's always done the pressure thing (we've lived here for 2 years), but the temperature varying is a new thing.

Do you have a combi boiler? We have the same issue and I'm pretty sure our ancient combi boiler is to blame (as is every single tradesperson I have asked who have seen the boiler). It's gradually become worse over time - we used to be able to keep the temperature somewhat steady by running a hot slightly in the bathroom at the same time but even that's not enough sometimes, and washing the dishes with hot water downstairs chokes the water supply upstairs. We really ought to replace it.