Mixer Shower gone HOT HOT HOT then NOT NOT NOT

[kato]

Our mixer shower suddenly stopped adding any cold to the mix scalding a guest using it. As soon as you turn the temperature to colder the water stopped coming through. Then cold water dribbled through even when it was off. Living without water until it's fixed so any thoughts - is it terminal?

also - Even when the on off valve is switched to off hot water runs through.

 

[mogget]

Is it a Croydex H2O shower?

They were round and plasticky with a big dial-type knob in the middle, available in white or a range of jazzy colours.

 

[kato]

No. no brand on it, it's round and very metal. Another one of the cheap and cheerful David McClean standard fittings in the flat we own.