Iphone Charger not working

Reference is made :<br> PART NO: applm<br> EQUIPMENT DESCRIPTION : MA591<br> SERIAL NO: Strackingnumber:***<br> IMEI NO:<br> <br> I bought an iphone charger about a month ago, it only worked for a week. I kept the box but the slip misplaced, this past Saturday 20 July, I sent the unit back. First thing the lady who helped me was very rude, I didn't get her name but she is Vhenda speaking. She told me that the unit is not Apple product, in which case I told her that thats what I bought from them, she started making subtle accusations that maybe I lost the original unit or I got it swapped with somebody else. After a long exchange of words they decided to book the unit for test. I just got the call now from the store that the unit is ready for collection but they cant exchange because its not an Apple product. <br> Now, how was I supposed to know when I bought the unit from the store that it was not \their"product? I buy lots of Apple products ONLY at iStores"