Rain dont stop wifi on month to month contract let monies accumulate

I have a month to month contract on their 4G wifi, my payment is around R500 per month for unlimited. All of a sudden after I lost my work they start trying to take nearly R2000 off for the last few month, now about 3 month that they want to deduct this high amount out of my account, I asked them how they get to that amount to no avail they just carry on with their own things. I don't have money in my account so I accumulate penalties which I must pay, this is ridiculous and not very bright from their side. Will they pay my penalties while they only carry on with this nonsense behavior of theirs. Just check my account now all of a sudden it is R2395 that I owe them, but my contract is month to month. All this companies are croocks and try ripping people off. I told them I lost my work already few month ago the Router and Sim is in my garage nobody can use it but they charge me for something that if you dont pay it is suspended untill you make a payment.