customer rights violated

helo Peter I'm very annoyed with the people of this company...so last year I got an sms saying if I want R55 free airtime I should reply with a yes a I did minutes later I realized maybe I was being ****med I then rep**** no again time went by without a feed back of who sent me the message because there was no company name on the sms or telephone number to call them back....ive been receiving airtime I think for like 7 or 8 months I called Vodacom to cancel me but they said it's not them..so recently I got a new fone for my birthday as a gift only to find out it uses the smaller sim than mine so i had to do sim swap cause my fone got lost so when i called Vodacom for sim swap they told me I need to call the company I did they told me I must buy a contract sim card...so basically I'm now a contract user without my knowledge no one called me to explain the terms of this reply that I sent.my rights are violated im now attached to the contract that I didn't sign or agree to..the company is ******** people I'm a student for heaven sake...i have been using this sim card for the past 15 years I'm really not okay with this at all