Why is upgrading with Vodacom SUCH a nightmare?!

WHY is it so difficult to do an upgrade with Vodacom? When you have a number that is due for an upgrade, they just about HARASS you with the phonecalls, usually at the most inconvenient times, so you are not able to do it when its convenient for them. Then when you are ready and able to do the upgrade, there is NO getting through to a call center, the website is completely pointless to do an online upgrade. Physically going into a store is also an exercise in futility.. there's no stock of the phones you choose etc etc... I want to cancel my contract with them, but that's another nightmare altogether! Oh but taking out a new line is nooooo problem whatsoever!!!!