Add's data


My home internet service has been down for 8 days. I'm almost at the end of my data cycle & I have been alerted that I have 7% left for the next 11 days.  I can pay $15 for add'l data, but I was told I could do this for $5.  It says, I haven't been charged which confuses me because I do have 7% left.  This has never happed before.  My home internet service is AT&T and all that outage increased my data usage.  What should I do?