No futher communication or call to finalise Application

Good day I was approved for a cellphone contract on the 7th of April on condition that i choose an alternative handset as the one i chose was out of stock, i received an sms that i will be contacted within the next 24 hours to finalise the deal, since then i have received no further communication or feedback, i contacted the call centre and i was advised that an agent will call me to finalise, yet days later no call no feedback, i tried online chat, no response, chat window closes after 2 minutes, please can anyone assist so the application can be finalised today ? Thank you