Plumbing Questions? Ask a Plumber for Answers ASAP
What is the current temp for the hot water, and what happens when you go to increase the temp does the number just flash but not increase?
The fault appears to be with the control board as the range of acceptable temp for the CH starts in excess of 40 deg C, so it suggests its only showing the current temp of the CH loop.
A new control panel will be very expensive (around £200 from here), for this reason suggest you seek to get a fixed price repair and protect plan.
British Gas do a fixed repair plan which can be found here.
Please let me know if I can be of any further assistance.
I can talk you through this process, but I dont think this will resolve you fault.
If you hold down the CH Plus and Minus for 5 seconds (which are the bottom two buttons), the boiler will reset and then go into engineer mode allowing you to run it at 100% and you can adjust the performance by using the up and down buttons.
Press the two buttons again together and then the power button to exit from the menu.
Do you require any further assistance?
Do you need any further assistance Vincent?