Unskilled Consultant and Bad Customer service

I am super angry at Cell C and their unskilled consultant. They always don't disclose the whole information and then expect to say sorry. Their sorry has caused me a lot of money and anger, they don't even show empathy as long as they not the one who are affected. I recently took out a sim only contract for R250 and yesterday they debited my account for R638 and then they say its for testing my account. What type of game is that why didn't they try the exact R250 and why would they try that when I already have an existing account with them. Where do I get money on the 9th when I'm only getting paid on the 25th. Who is gonna pay for the negative balance on my account, and if it was a test why do I need to log a request for a refund...CellC is truly taking me for a ride, I have never been so drained, ever since I started with Cellc i don't remember being treated like a customer should be treated.