Deceiving Billing Practices

I am confused how how AT&T quotes it's billing. 

In December, I upgraded from Spectrum to AT&T fiber, a great upgrade as fiber is great & reliable product. Given I am an existing AT&T customer with an unlimited and and would have auto-pay, I was quoted at $60 a month. I agreed and an agent came next day and installed the new fiber internet. 

Works wonderfully! 

After getting billed the full $80 ($85 first month, but that makes sense from timing) for every billing cycle, I reached out in April over when the $20 credit would be applied. The agent on the chat feature assured me that I will see it in the next billing cycle, May. I received the May statement and it is once again, $80. After online chatting and a phone call for an embarrassing amount of time, I guess I have to (Edited per community guidelines) it up and pay the full $80. 

If I would have known this, I would have simply upgraded the Spectrum service I was receiving or would have gotten some other equipment to help with the lagging service. Definitely disappointed in how I was deliberately deceived by AT&T. Am I going to switch back to Spectrum? No, fiber is awesome and is worth the $80/month, I just wish they were more upfront with the billing.