Terrifs Change

I mistakenly changed my call tariff, now I want to change back and they tell me I can't change back. I called the call center and I was told to wait for end of the month so that I can be able to change back. I called again today and I am told that the terms and condition of the tariff that I am on doesn't allow me to change back. I asked If the only option that I have left Is to leave the network and the person on the phone tells me that I can change If I want since there Is absolutely no way I can change that tariff back. The call charges on this Smart broadband WIFI network are **********. I can’t even make a 5 minutes call with R30 airtime.