New phone specs not correct

I have telephonically upgraded the 7th or 8th March 2016. The agent said that the new phone will have 16Gb internal storage, but after I have received my handset (Samsung J5) the 14th March I have realized that it only have 8Gb internal storage. After 27 min on the phone to cell c and 7 people later I still dont have an answer. The last person I spoke to said that her supervisor will contact me, but no one called. You are happy to upgrade someone, but when you mess up no one can help you to resolve the problem. You have given me false information and I need this issue to be resolved. Regards Frans Jooste