Upgrade???

I am currently on my mom contract, I phoned 4U Vodacom in Alberton City this morning to request an upgrade, where they told me I only qualify for an upgrade in December. My mom (account holder) and I upgraded last time on the exact same day (2013), we also received our new phone the EXACT same day. How is it possible that she upgraded a week ago to her new contract and I have to wait for December. Can you please assist asap, as I have problems with my current phone, and need a new phone.