I'm desperate to find the cause & hopefully a solution to why showers not getting hot when the sink hot tap in the same bathroom is. Is it to do with the three way valve, the shower valve, or what?? I'm struggling to find a solution online so asking for help.
I haven't had a hot shower for a over a week now so I'm getting pretty desperate, can anyone please help?
Thanks )-:

What do you mean by three way valve? Do you mean three handle, hot, cold, diverter?

If so, do you get any hot water when you open the hot side only?