Getting charged for Mobile Service before it's activated and the phone number hasn't been ported from AT&T

I was told to sign up for mobile service by the agent while calling to setup internet. I was told i would get $500 gift card for switching a carrier on the first line and $300 gift card for the second line after 24 hours I should receive an email.. waited nothing showed up and I let the time go by trying to contact the agent again was not successful... so a month went by no emails for the gift card... I didn't activate the SIM yet, i wanted to make sure I get what I was promised before I switch carrier from AT&T.  Now I checked my online billing account for mobile and I have current charges that not due yet but will be for $80.00 !!! What is this nonsense... first totally lied to get me signed up or didn't provide what was promised and now I have a $80.0 bill that will be charged for phone lines that has not been activated and the number is still under AT&T, not sure what am I paying for!

It has been a horrible experience with customer service... was told the $80.0 would be credited within 24 hours and here I am after 24 hours still nothing in my email.... when reaching out to customer service they have no idea about the 40 minute long call I had yesterday and keep telling me since I have SIM card I have to pay even though I didn't use the service and the phone numbers are with AT&T! Not sure what to do from here...I haven't activated the SIM waiting until the issue gets resolved, but looks like i might get charged for next month as well even though I am paying for AT&T for the same phone lines... this is ridiculous! I haven't even discussed with customer service what happened to the $500 and $300 gift cards that were promised!!!