bad service and empty promises

In October I bought a Samsung S4 mini and the phone was faulty from day 1, I took it a numerous times to my nearest outlet when they finally told me to take it to Samsung for an software upgrade which they promised me it would be fine and only to find out the phone was worse than before, Cell C the eventually advised me to take it to the nearest outlet to book it in for repairs which I did on the 6th of Jan 2015 and their turn around time was 7 weeks and during that time Cell C never made contact with me , nonetheless today I was told to collect the phone and when I got to Cell C in Midrand I was told the was a fault with the battery and that the phone was delivered but the battery was not delivered and the agents would not help me much and when I made contact with the customer service to cancel my contract after a numerous attempts to fix my phone which they never did they told me I had to pay a cancellation fee which was equal to the monthly instalment left on my contract and I feel that is unfair of Cell C to expect that of me whereas as from the start Cell C gave me a faulty phone and they not willing to accept their mistakes instead they give me a run around.