7days change of handset

I was at the Telkom direct store now.When i renewed contract i took a LG phone the guy who helped me said I can check out phone and return within 7 days if the phone is not suitable for me.I then returned it within the 7 days and the other guy who helped me today said i cannot return phone and i have to pay R800 cancellation fee and pay device cost for this phone that i dont want.All i wanted was to exchange phone for the P10 lite on my contract.