Rain false advertising? Over charging?

I started using rain 5G, and after a couple of months we moved from Western Cape to Gauteng and the area we are living in had no 5G service. We cancelled our service until we are in an area that has 5G again. We noticed that Rain charged us a whole months worth of subscription in the beginning of our contract. On my query of the amount I am told that it is for the device? BUT YOU ADVERTISE FREE-TO-USE Router?????????