Awful customer experience

I am trying to migrate my existing data contract to the highest package available and have contacted cellc customer service mutiple times, a case had been logged I get a miss call from the company once and no one tries to contact me thereafter. The second time I contacted they did not even try to call me they just sent an sms I needed to contact customer service for feedback and the feedback stated they were unable to migrate me to a top up which I never requested. If someone could contact me they would know what I need but it seems impossible to get someone from the migration department to speak to.