Double charge for a single service

Hi,<br> <br> I have a myChoice contract with MTN and in Feb, I loaded airtime onto my sim so that I could sign up for BIS while waiting for MTN to get the phone that I wanted on my new contract. I loaded the BIS bundle onto my phone using my airtime and when I found that it did not work, then I contacted MTN Customer Care who indicated that she would need to activate it on my sim. After confirming that I would not get double charged, I asked her to go ahead. I only used the BIS for a few days and then called back to cancel it. When my account came at the end of the month, I found that I had in fact been charged for it on my account as well as paying for the budle with my airtime. I have been contacting MTN to resolve this issue and after numerous emails and one redirect, I am still no closer to a resolution. I hope that exposing them here will yield a response.