Misinformed

I wanted to purchase a phone for my son who needed a phone for school project then i went to Ackermans and was informed by the saleslady that i can deposit a phone and pay instalments for 12 months at the end of the 12 months the phone will be mine only for me to google terms and conditions after the purchase to my suprise i found out i was renting the device and will be charged again for the phone to be mine an amount extra i tried cancelling the whole process and get my refund to only be told that i have to pay up the rest of the instalments for rental and return the device. I dont want to rent the device if i was informed of this arrangement i would most probably have taken a contract phone instead of renting a device