How can I get my central heating to work again?

I have a valliant eco combi boiler & a sunvic remote thermostat & receiver. Both water & heating were working fine, but now the heating won't come on. I noticed the battery light was flashing on the thermostat & have replaced them but heating is still not working. I am sure the receiver had a green light next to either the test or install button but now neither are lit, however a red light comes on if I press the install button but nothing if press test button. Is this a job for the big boys or can a blonde techno-phobe sort it? Any help would be really appreciated