radiator hot all the time

Took the TRV off and the pin is stuck won't budge for anything. Turned the lock shield valve off and it's still blasting ??

Hi I have a Potterton Profile 50e supplying hot water to a copper tank. There is a pump off the cylynder for the central heating system controlled by a room stat. There are no diverter valves (single or 3 way) anywhere in the system. My bathroom was re-plumbed 2 years ago and a standard single...