2000 clio 1.4 dci heater plugs dont engage

My Clio recently developed a bad habit of not starting when i tell it to. I have to turn the key repeatedly before the heating plug symbol lights up so obviously i can't start the car. I've had the heating plugs changed and if anything it's worse. I've had a warning light which says stop and now when the plug light turns off the engine doesnt always start. I would appreciate any advice or information on how similar problems have been resolved.

Cheers

Kaydee