how can i fix my boiler?

i used a 3 amp when i changed fuse in my banfoss timer switch plug because heating wouldnt fire up to come on it made a sizzling sound so i switched off quickly ,then i changed the fuse again the same noise happened then it suddenly blew before i could switch it off did i use the wrong amp in the plug and can i fix it as its the only means of heating ive got and its really cold throughout the house im desperate for any help

ruth
December 2012