Baxi duo-tec 24 heating not working?

Hi can anyone help me? I have got a new (6 months old) Baxi Duo-Tec 24 combi boiler (just bought house so I don't have warrenty/instructions, etc). The boiler seems to be working fine as we have got hot water, but the heating has suddenly stopped coming on.

We have got a separate, remote timer (battery-powered) and I have replaced the batteries and everythi g is switched to ON. I have gone through the troubleshooting in the user guide and nothing points to
this error. The boiler doesn't actually come on and radiators are cold. But if I turn the hot tap on everything is fine. The heating and hot water icons are selected on the display and up to today it has
worked fine.

There are no error codes displayed, although there is a red flashing light on the "optimal timer" panel (the outer light).

Any ideas before I call out a repair person? It is very cold and I am literally about to give birth so I ***NEED**** the heating to be working ASAP!!!

HELP!!!