Your boiler is currently indicating that it is switching between its summer and winter operational modes based on the position of the control dial.

DIY fix possible

Turn the heating control knob fully to the left and then back to the right to reset its positionSwitch the boiler off at the fused spur for 30 seconds to allow the internal electronics to rebootEnsure the knob is firmly pressed onto its spindle and is not obstructed by the casing