Altered terms of use mid-contract !

Vodacom decided to change my contract terms without my consent or approval. The contract i signed stated specifically that I could use my data sim card in the home router and my cellphone. I have been doing so with no issues till last week. I called vodacom and was informed that the terms of use were changed and I can longer use the sim card in my phone. This new deal is highly inconvenient for my family as mu kids do online schooling and in the event there's no power they can longer attend classes as there's no longer network ,whereas previously they could insert the sim card into a phone and continue with classes. Vodacom is now attempting to charge me extra if I "breech contract" whereas they changed the deal to no longer suit my needs. I am highly disgusted and disappointed as I've had this contract for longer the 2 years! The least they could have done was wait till the contract i AGREED to was over before making these selfish changes!