In reply to chai:
The best gear shop of which I am aware in Chiavenna is:-
Effe Tre Sport
Viale Consoli Chiavennaschi, 23022 Chiavenna SO, Italy
Lecco shops would have a bigger selection, though.
In Switzerland, the best shop in my experience is Govertical in Pontresina. That said, it is significantly more expensive than Italy - however, the service is great and it is run by guides who have a good awareness of equipment requirements. It is also the best place in the valley for conditions reports.
Hope this helps.
L