Pathetic Service Received from Voadacom.... and its not the first time!!

last month I logged onto the Vodacom website and an sms was sent to me advising that I was due for upgrade. At the same time I decided to preorder the Samsung S9 in order for me to upgrade to that. On a Sunday afrternoon, I got a call from Vodacom's upgrades department advising that the S9 is now available. I informed her about the sms I received regarding my upgrade. long story short, she processed everything and confirmed that there is no outstanding balance on my contract and therefore all has been processed and I will only be billed an additional R150.00 once off for the upgrade. I confirmed all in order and to proceed. I asked her to check if another contract of mine was due for upgrade and she confirmed it was. Same story, no outstanding balance besides the R150.00 once off. This month I get my statement on 16/04/2018 only to find that I have been billed an additional R1600.00. I called the call centre 17/04/2018 ( nevermind that I had to hold on forever as always) , I had been advised by the consultant that there is handset charges on both the contracts as my contracts were not fully paid however they can still do upgrades. she told me that my bill will be this high for the next three months in order to pay off the other handsets. Anyway, I told her to escalate my query as I will not pay this bill since I was not informed of this. She advised that someone will contact me and to date, I still have not received a call from anyone at Vodacom. I have been a loyal customer for over 10 years with Vodacom and have over 5 contracts with them, I really think it is unfair that I have to be treated this way. Should this be the case, I will have no other option but to move my contracts to another service provider!!!