Billing issues unresolved but increasing

I could give them more stars because I have coverage although it goes on and off... However I have a complaint about my billing and need them to adhere to my concerns... They sent me two sim cards when I ordered 1 and didn't know what to do with the other sim so I asked them and they told me that f I used it I will be charged, I have not used it and only inserted it once when the other one had no coverage and took it off the very same day... But guess what? I am being billed on both, I've asked them to resolve the matter but I have been waiting with an increasing bill that is not in my budget. I am a social entrepreneur and use rain to connect to the internet as some software for teaching children requires the internet and found it convenient to connect with rain in educating my students. I'd like to continue using their services but I can't with an increasing bill that I am unable to afford. Please help as I am out of my wits end and miserable...