Hot water to all of my house except master bathroom

[Geohowden]

I have a Vaillant ecotec plus 838 boiler and yesterday morning I used the shower in my master bathroom and it was working fine with plenty of hot water, however that evening I went to have a shower and there was no hot water, so I tried the bath and tap in that master bathroom and there was no hot water there, however the taps in the rest of my house and my upstairs shower work fine with plenty of hot water, what could be stopping it from coming to my master bathroom?
Attached are pictures of the boiler setup

 

[Unvented cylinder reply]

I mistakenly thought the upper controller was exclusively for immersion heaters, but I'm wrong, it's for combi systems.
I rashly assumed that the boost button would operate the upper immersion, but suspect it actually will trigger the boiler, in which case the experiment to try it will do nothing!

Try turning on the white switch for the upper immersion heater, below the one that's already on. That should temporarily give you some hot, but at electricity prices!

If the lack of heating the cylinder is down to the 2-port valve being faulty, you are going to need a plumber.

Yep, turning the immersion heater on gave me hot water, but I'll try and get a plumber in to sort the problem fully thank you for your help