Contract decline with no valid reason

My contract application to add a cell phone on my existing data contract was decline with no satisfactory answer ( reapply after 90 days) tried to call the customer care, have been send back and forth. Call centre agency advise me to send ID copy and proof address. After two days still no respond. I called the call centre again and been told to go back to the Vodashop. The vodashop is sending me back. I cannot afford to wait 90 days just to get a new phone. Can anyone tell me why I need to wait for 90 days just to add a R329 on my contract. For the past 12 months has not missed any payment. I'm already spending a lot on prepaid want to move over to contract.