Horns have adjustable contacts which wear out over time. There should be an adjusting screw on the horn which may be covered with a blob of sealer. Try fiddling around with the screw to get the horn working again.
Hi, more then likely it's the horn thats faulty quite common on punto,when you replace turn it so the outlet doesn,t face forward.Halfords have a horn suitable on offer at £9.99 or Ring horns at £14.99each choose between high/low note, I prefered the low note.
Simply earth one contact on the horn and run a link wire from battery to the horn. If it sounds properly (rather than just going honk) the problem isnt the horn itself.
fuse or its probably got damp, unbolt it and give it a blast with hairdryer, then adjust the tone...if doesnt work cud get 1 from scrappies for a few quid