Heating problems?? I've not had proper heat for the last...keep on for it....2 months!!...

I've not had proper heat for the last...keep on for it....2 months!! My heating comes on when it feel like it and go off when it like. either we own spooks or something has gone wrong. There is solitary 1 radiator that is working downstairs, but the rest upstairs adjectives work despite being flushed through and we hold also bled them all.We've changed the pump, and the thermostat, so be wondering it it sounded like the time clock which is on adjectives the time. The water is on as resourcefully and we have no problem near that. If anyone can help i'd be eternally grateful.
Answers:    you could be right roughly speaking the clock but the best thing to do is bring a free estimate from a qualified plumber then you will know how much it will cost ...you inevitability to get a few estimates first consequently you can choose the best one good luck ......ps i bet your freezing its so cold tonight !!!!!!!
sounds similar to a job the gas board or the equivalent corgi registered person. i always have mine serviced every year and paid lb100 a year , that included insurance for breakdown, and have a new pump finishing year and didnt cost a penny.
your boiler may want replacing.