Boiler and boiler pump not stopping

I have a Boilermate 2000 with an Ideal Classic slimline boiler. I have noticed that when the store temp reaches the top number where it should be satisfied, the boiler and boiler pump are not switching off, the 2 leds are still on, the boiler still fires up and the pump continues running.
However, it stops if their is a call for heat either from the central heating or the hot water, as soon as this happens the boiler led (1) goes off, the boiler pump stays on for a bit as it should then goes off if the temp doesn’t drop too low (if I just run a hot tap for a bit then turn it off). If I leave the heating on the temp drops below the bottom threshold and the boiler comes back on as it should. But if the heating or hot water are not on, the boiler and pump just keep going even once the top store temp is reached.
I thought maybe I was going to have to replace the whole ACB but I saw a thread from a while ago with the same problem and they said they had done that with no change. The last they said was that they were going to change the store sensor but then there are no updates on if this worked. If I cycle through the sensors on the ACB I don’t get any error messages but could the sensor be the problem? Anyone got any other ideas? Thanks.

Hi Jordan, I have had this same issue going on 4 years now and have been unable to resolve it. I have replaced the PCB (multiple times) and the thermostat on the Boilermate, and the PCB and various other components on my boiler (a Glowworm Micron 40FF), all to no avail. Both British Gas and Gledhill engineers have looked at the issue, but could not resolve it. Gledhill pretty much just said the Boilermate was scaled up and was end of life and needed replacing. It’s 23 years old now and, apart from this annoying issue, works perfectly in every other respect.

If you manage to find a solution, please let me know!