Upgrading contract without my consent

Received an SMS saying my 'quotation has been processed'. I had a missed call from an unknown cell number just before this SMS. I have NOT SPOKEN to a Vodacom representative. Went to Vodacom Shop Bedford Center who called Client Services, as it was noted that my contract had been UPGRADED WITHOUT MY CONCENT. Surely this constitutes a type of ***** from the Upgrades Department? I did NOT agree to my airtime being increased from R140 to R200/month. If you look at my account, I often do not use the airtime - I use far, far more data. How can the Upgrades Department upgrade me and increase my airtime without my consent? I spoke to TINA at Customer Services, who said she would sent a 'Cancelation' request to Upgrades . Tina said there is NO reference number for my call. How can this be? Surely if I lodge a complaint I am entitled to some type of reference as proof, especially when this was an upgrade that I did not agree to and had nothing to do with? I am really concerned about Vodacom making changes on my contract without any written discussion or consent with / by myself.