Baxi back boiler not working?

Hi,

i have a baxi back boiler for heating/ water. My room thermostat started making a buzzing noise a week ago just before the boiler fired up. Yesterday got up to no heating, wacked the thermostat up and heating came on. This morning same problem but wouldnt fire up when i turned up thermostat. Ive turned clock, bolier and thermostat off to see if just needed re setting but now pilot wont stay lit. Is it my room thermostat thats broken? Brrr coldest day of year for it hey!