Unfair treatment

I'm seriously having a problem with Ackerman's located at Elspark regarding the device that I bought on the 1st of November on the following day when I was backing up my stuff on Google, the phone started getting extremely hot, I then took it back to the store...the store booked the phone for repairs instead of refunding me or giving me a new phone . Now the phone is back from repairs but I don't want that phone anymore I just want my money back ,they are refusing. They as it's either I take the phone back or I cancel the contract & I must pay a cancellation fee . Like how because I have never used that phone .