im unsatisfied with the LG G4 phone

Good day , on Wed. 4th Nov 2015 I went to upgrade with my cellphone contract. it is now day 3, I'm still in my 7days grace period of my new phone but I'm unsatisfied with the LG G4 handset-i still can take it back within 7 days to change the phone to another phone? But the vodacom branch at Fourways mall refuses to help me.they upped my contract from R349 to R449, I don't want to pay R449 for a 24month contract for a phone that I'm not satisfied with. <br> Please help me. Or assist me on what I should do.<br> Thank you