I got two Samsung galaxy watches yesterday.
The salesman said I would need a plan and two shares to get the watches to work. Since my wife is with Telstra.
She got her watch and found it paired it with her device and under Telstra it would work.
So I do not need one share and the plan. Apparently I need to pay a cancellation fee even though I cancelled it within 24hrs.
I see this as unfair because I thought there was a cooling off.
Well the representation that the watch required an Optus plan to be functional should be enough to cancel the plan without issue. It sounds like an innocent mistake and it seems you've already been told it has been resolved? So that sounds like a good outcome.
Cooling off periods apply only to very specific transactions (auctions, car sales, telemarketing and door sales mostly). All other contracts you sign are generally binding from the moment you sign them (unless stated otherwise in the contract). You can read about them here (at the bottom of the page)