Cannot migrate my Month to Month contract to a more expensive package!

<p>Since 8 August 2016 I've been trying to upgrade my month to month contract to a higher package. Cell C have closed my ticket twice and fail to call me. I've followed up with them on three different occations and have asked 3 times to speak to a team leader who are always out but WILL call me back, yet they never do. I guess Vodacom is the better connection after all...</p>