Rip-off package do not take it!!!!!!!!

Cell C had offered me 5 GB daytime and 5 GB nightime data package for R85 a month. last month alone i paid R500 and i did not recieve the 5gb mentioned. instead i recieved 500mb. today i recieve an text message saying i owe them R193. when i check the status of my data, i only have 200mb left on day time and 700mb of nightime data. when i check my data usage in my phone settings, i have not even reached 500mb of data usage!!!!! complete *******!!!!