Cannot connect since i cancelled my contract

Hi. I had a vodacom contract for the past 8 years... i cancelled my contract in june this year and i experienced issues trying to connect to the internet thereafter. I called the guy who did the cancellation and he noticed that he forgot to change a certain setting when they converted me to prepaid.. internet connectivity was great! I have for the past week been connecting to my wifi at home and work because when i use my vodacom mobile data, i cannot connect to the internet .. my Vodacom modem also gives an error saying "connected, no internet".

Im at a height of frustration and would appreciate for someone to assist.

Regards Rasheqah