Missing Air time

Good day I have 13 contracts currently with Vodacom A consultant that assisted me when I called in regard to missing airtime today and told me something shocking Most of my contracts are Top up contracts and I was told by the consultant that if i do not use my airtime that it falls away i do not agree with this i pay allot of money every month for my airtime and do not understand how Vodacom can just take my airtime as they wish I would like all my (fallen away) missing airtime to be reallocated to my accounts i have paid for the airtime and they cannot just remove it as they want this does not work like this

I need a manager to contact me asap regarding this and give me a resolution

My main contract number is ********** 469 (this will apply to most of my top up contracts)