Dishonesty and ridiculous billing

I have been with rain since 2020 and never have i ever been this angry about the service provided to me firstly in the past rain was advertised as a month to month i in the past didnt pay for a month and they would cut off the service and id pay the next month no problems recently i stopped using the sim card because i was having connection issues so i thiought matbe it was the area that was in April i now end of August tried to reconnect the service and they told me the sim card was faulty i did the sim swap it came and last week Friday i got cut off again and they said ti have to pay another R499 thats absolute nonsense they have been charging me from April over all the months and noe they say i owe about 1500 where as when i joined it was stated if u don't use the service u dont pay so how am I now being charged for months where there was no data usage im so annoyed at this because we as customers are inconvenienced i use the service to do my work during the day and if im just going to get cut off like that it means i cant work wich may eventually lead to me losing my job... I haven't made provisions yo be paying extra data for the rest of the month... What am i supposed to do now.?