Promotional wifi being charged without consent

I've been getting alot of missed calls from ********** 120 and finally today I decided to answer it. It was a lady who said she was calling on behalf of Edgars saying they are running a promotion of giving customers data free of charge for 30 days and if you're happy with the service then you can subscribe with them and they will add the amount onto the Edgars account. The lady said I'll receive a text afterwards confirming this but now I received a sms saying my wifi direct will be charged at R78 yet I didn't receive anything . Just saw other people complaining that they are being charged for something they didn't agree to so can you please make sure I'm not charged for this as I didn't agree to it.