7 day replacement policy a load of bull

I was told I could exchange my phone for a brand new kne should I experience and problems within 7 days. Yesterday within the 7 days I went into the store to complain that none of my GPS services work. The consultant tried a few things and said I should try again that day. I did and it still did not work. I went back today still within the 7 days and they then said they would replace it. Whilst busy with the computer forms I imagine for replacement I was told they cannot replace it due to a sticker missing kn the box. This is the sticker that is used to swal the box so naturally it would be pulled off. I was never informed that this sticker needed to be retained in order for replacement to take place. It would seem to me that Cell C will try their luck at anything not to have to live up to their 7 day replacements policy.