Rain changes speed to make more money

For the past few months I have notice that my speed automatically changes from 30 to 60 Mbps, the last time I called and had them change it. Noone has made changes but every month from the 19th I get it changes so that I can pay more on a monthly basis this is not hat we signed up for Rain is becoming a problem now From 599 to R 799, who must pay the extra amount. and the quick to tell you your service is cancelled. Some one in technical must call me now