Help! Reduced flow from hot tap.....

Southend1

Hi guys. Just wanted to update this thread and thank you all again for the advice. Dad came over today with his large adjustable spanner and between us we managed to get the headgear off the tap. I think what happened was a bit of carp had got in the tap gear and was stopping it from opening fully. We gave it a clean, popped it back on and now the tap turns 4.5 turns and I have lots of lovely hot water again. :j