My contract was changed with no consent from me

I signed a contract with Nashua Mobile with a Cell C sim for 2GB data each month (1GB anytime, 1GB nightime) and 50 minutes - when my data for the month finished i got an sms that gave me option to purchase more at a data rate. I had this for 2 months til Nashua Mobile closed down.<br> Now Autopage - I found out the other day that my contract type has been shifted to that of 100sms, 100MB of data and 100 minutes. I was given no communication on this and when this data runs out, i do not get an sms offering to purchase more meaning I am being changed a call rate for data use which is approximately 99c per minute which is absurd. Now I am billed an amount I cant afford which is just over 4 times the amount of my usual bill with Nashua.<br> Im being *****ed! Be careful out there.<br> Autopage/CellC im saving for your next Sandton billboard!<br> <br> I hope I hear from you soon to resolve this!