Boiler goes to standby (off) after a while since fitting Tado

Options

Just had my Tado wired in today.

When the plumber as here I did a quick test with the wireless thermostat and it appeared to work fine.

I went out and came back and noticed that my boiler (intergas eco rf 30) went into 'standby' or 'off'; additionally I can no longer trigger it with my wireless thermostat anymore.

The test mode on the receiver seems to trigger the boiler okay though - any ideas?