Phone incorrectly disconnected

I have a small business plan. I signed up to renew a contract last October. However ATT didn't implement the new plan and started charging me more than double. I called in about 2 months ago and was told by the agent that it shows my plan was confirmed but not implemented. I will have a new plan with the lower rate implemented, plus credit for over payment since Oct 2022. Fast forward to last week when my service was disconnected. My new plan was still not implemented, plus the credit I was told was not added to my account.

I have been calling every available customer service phone number on my bill and from the website. I would provide my account info to the automated system, and put on hold due to phone traffic. After up to an hour sometimes, the automated system would say the ATT number is no longer working. My service was disconnected last Thursday. I have been calling in every day since.