Pressure on Jaguar 23kW combi boiler?

The pressure was down to 0.8 and I raised it but may have raised it too high to 1.9. This has resulted in the LCD display flashing and the heating turning on and off. When it is switched back on at the mains the heating comes on and stays on for 30-60 mins but cuts out at the pressure rises to 3.0. I have been told I need a new central heating boiler - could this be the case? Alternatively I have been informed I need to have a new PCB and exchangeer fitted at a cost of about £600.