Cancelled a new contract, now billed for it

I took out a new contract, where the deal was 2 x Samsung A22 phones, with 50 minutes and 500 mb. Chose the 36 months, and the deal changed to 1 phone only. I returned the phone the very next day. Now I see I am billed for the phone!!! I cancelled the deal, why must I pay? I didn't even open the box or the sim card. Please assist, this is really not good service.