It ain't that hard - but do it on a warm summers day - or indoor ! You need to b end plastic without deforming or braking it !
After removing all screws under the bonnet...eh - all screws holding the top of the grill etc ;o)
The horn is on the right hand side in front of the radiator.
Gentlyn pry the plastic top sheet, You just removed the screws from - and find i.e. a block of wood to keep the opening....open. You only have two hands, so keeping that bugger open is a great help.
Either exchange it with a original horn - or replace it with a Claxon-type as I did.
Paid something like 10 $ for it - including shipping from mainland China to Copenhagen, Denmark - and as it is two horns with plenty of low tones and volume - it's lightyears better than the original.
Using "foreign" horns means that the original plug has to be cut, but if You are no stranger to a soldering iron - it's a fast (and better than original) fix.
Only grief is that the supplied mounting "arms" was so thin that I wouldn't use them - was afraid they would rattle against the radiator. Had an old mounting "bridge" for two horns lying around - from a Volvo. Just needed a little bending to accommodate the new tennants ;o)
So - a little fiddly with somewhat small access space (especially for my big hands), but absolutely a manageable DIY job for the home mechaninc.
And You'll never be embarrased to use your horn again ;o)