Sorry, didn't see the "burial Geneva".
I do know that someone on here managed to obtain information on a UK citizen's death in Switzerland but cannot remember who it was.
However, I typed "UK Citizen died Geneva, death certificate?" and came across one or two forums who gave this address:
Office Municipal de l'Etat Civil
37 rue de la Mairie
Case Postale 6327
1211 GENEVE 6
Switzerland
email address;
etat-civil@ville-ge.ch I believe they are very helpful and will most likely speak English if you prefer.
I think this is for deaths in Geneva town. If it was outside Geneva, they may still be able to help you.
It's worth a try - you could also type in what I did, or similar, and see what comes up.
Gill