thermostat wont go below 85 degrees

I was told when I wanted to disconnect my service because I am moving that it could not be prorated. I was assured my thermostat would work .Now, my thermostat won't work. I wanted to end the service on 7/25 , I was told by the representative that your company does not pro rate , therefore I was forced to terminate my service on 7/11. Immediately  following the disconnect ,  the thermostat  was not functioning properly and will not cool below 85 degrees. Living in Texas , the average daily temperature is 105.  As you can see, this is putting my health at risk. I am moving packing up boxes, sweating. I tried to call and remedy the situation, but the representative told me " she would do nothing to help me because I was not a customer " as of 3 days although I have been for years. She would not put a supervisor on the phone to help me...AGAIN.. because I was not a current customer...even though I have been for many many years. I have been a LONG time customer with ATT and not for her to put a supervisor on the phone. I didn't want to cancel, but y'all are going out of business. I would have taken yall with me , but  yall are going out of business. Please have someone call me and tell me  how I can have this thermostat fixed.  <edited per community guidelines; please do not post personal information>she kept telling me she couldn't get a supervisor because i wasn't  a customer