Cash Back on i-phone upgrade

I saw the ad that Apple will pay up to R2000 for your old i-phone 4S when upgrading to an i-phone 6 or 6+. As I was eligible for an upgrade I went to the Apple Store in Sandton City rather than the Vodacom outlet. I then put my name down for the upgrade for myself, my wife and my daughter. I chose an i-phone 6+ while they chose i-phone 6's. This was in November. The shop phoned my last week (end January!) to say a 6+ was ready for me (My wife & daughter are still waiting for phones despite there being phones available at some Vodacom stores).<br> I upgraded but when I took the Certificate (you have to go on-line and register for the R2000) and the phone with it's original box and charger for testing, they told me it failed its battery test and they therefore couldn't buy the phone from me. However the battery lasts me a day and a half, just as it did when new 2 and a half years ago!!!! <br> I thought Apple were buying the phones to destroy so as to stop them going into the 2nd-hand market, so is this a **** to make you buy from the Apple Store????<br> By the way, my wife and daughter are now going to buy Samsung instead!!