Cancellation department

Ever since i have purchase the Samsung J7 prime dual sim phone online in the month of July 2017, so excited to have received my new phone.(i have also changed my network to FNB) as the week went into 2 weeks i notice i have been experience a network problem. (and i have had dual sim phones in the past and before this phone mention above. but never did i have a network problem). so ever since i thought it will go away. but it didn't. so i have called the fnb device department to help me with fixing on the issue faced with this phone. so the technical department as been telling me what to do and still it never helped, i thought maybe it was the fnb network and not the phone so i changed my network back to cellc and used the phone and still the same problem. ever since i have been calling the Fnb technical department and even they couldn't help me, so after so many months back and forth with Fnb they said i should go to the Samsung Repair center (i also taken the same sim cards and tested on another Samsung j5 phone and both my sim cards have been working fine). and i have taken brand new sim cards and used on the samsung j7 prime and still the same problem.) i explained my problem to the Samsung Repair center technicians and even they couldn't help so they had to assess the phone which i had to leave my phone with them for 3 weeks, and they replaced me a brand new unit. excited to pick up the unit and to have no more worries, just to find out that i am facing the same issues but i was also testing the phone and quite forgot about the 7 day open period if the phone is faulty to phone and send it back. due to it been the December period got caught up in December rush that i completely forget about my phone. and after that was New years rush. (which no one is opened at this time) In the first week of January i have called in to have this phone picked up as i didn't have the time to go back and forth and than wait another 3 weeks for my phone(to be repaired by the samsung repair centre). As i didn't have another phone to use. so i decided to cancel the contract - knowing in mind that i wont be paying a cancellation fee due to the phone been brand new. (as i have place everything back on the phone and neatly wiped and cover the phone back to its original condition. and also setting it back to samsung factory settings. as i have had many apps. so i couldn't send my phone to the assissing guys with all my apps on the phone). and how can i pay for a phone that is not my fault, and the phone is the problem (network problem issues) please put yourself into my shoes and see if you will be happy paying for a phone that is not your fault which is a network issue. (my friend have a samsung j7 pro and i have had a look at her network options settings, and her phone gives the options of one sim to be 4g and other to be 3g). and the samsung j7 prime gives the option of 4g and 2g and when someone will call me on the other sim which defaults to 2g the phone will go in a H+ mood where as i cannot hear the person on the other side. ( i hve tested my sims on my friends phone for like a week which she learnt me and it works fine. no issues and it does not go to h+ etc).

so the cancellation department wants me to pay for something that is not my fault. and using time period of the 7 day on me. as the phone is still under warranty and the phone is still under 6 months of contract. i dont have the money to pay for the cancellation fees ....