Cel C is robbing people

I took up a contract with Cel C December 2016 and I was told it was a 2 year contract as all standard cell phone contracts usually are. I took up the contract at Edgars in Greenacres Mall in Port Elizabeth and I remember clearly discussing the different options of upgrading after the 2 years. I paid it month on month with no issues for 2 years. And I December 2018 I decided not to renew or upgrade my contract. And no debit order went off in January and February for the debit order as expected but today 12 March I received an sms that my account is in arrears, I called Cel C customer service to seek clarity and a lady named Portia told me that my contract was renewed to a month to month contract where I'll need to give notice to cancel it after paying the amount in arrears. I did not agree to this renewal or was I made aware of it when it was done. When I told her she said it's in their terms and conditions. I AM REALLY NOT HAPPY ABOUT THIS.