worcester Bosch combi boiler?

It keeps losing the radio link with the thermostat and will not heat the radiators. I increased pressure as it was low thinking this was the cause of the problem but it hasn't made any difference. I keep resetting the link and it works for an hour or sometimes less then goes again. Had over a week of waking up to a freezing cold house and I getting a little tired of it now. Any suggestions would be greatly appreciated. The boiler is about 4 years old and has been great up until now.