Vodacom Live Subscription unknown - airG Gold

We received exactly the same messages since 10th April, and have not subscribed to any service. Would like to know the answer and how to ensure we don't get charged for this - message as follows - Thanks for purchasing airG Gold at R2.00. Get your free welcome tone [URL Removed] or *117*987*107#<br> <br> Another one received was Your subscription to airG Gold has ended. To continue enjoying these and other services click [URL Removed]<br> <br> We don't want to respond to this as we are not sure where it comes from.