Not sure what's happening to the store but we posted a parcel to the campsite at Cannich last year with no problems. There's also a decent pub, as well as a cafe on the campsite. I think they may sell odd bits & pieces at the campsite too but someone else might be able to confirm that. All of that enabled us to keep going until the shops at Drumnadrochit.
Hope that helps
Vicky

I would definitely hold off and re-supply at the Coop in Drumnadrochit. Only down side is its on the wrong end of town from the pier so a bit more walking involved. The shop with the local post office inside (much more conveniently located across from a pub) has some supplies, too. Another alternative is to ship your package to the post office in Drum. Good Luck!

I spoke to the campsite in Cannich a few days ago and they will be happy to receive a parcel for me - perhaps that is a solution for you too?

Stayed at the campsite last year - nice place, friendly staff.