Is there anyway to escalate a complaint regarding terrible customer support?

Let me start with a bit of context. I purchased an iPhone 11 Pro Max under the Apple upgrade program when it was first released, Apple care plus was/is included in my monthly payment. In late April 2020, my screen cracked. As this was right in the midst of the pandemic, all Apple stores were closed. I choose to have my device replaced quickly rather than wait weeks to have the screen repaired.

On April 27, I received my replacement phone and mailed back my cracked one. However, after a couple of days, I noticed my Apple care coverage was not transferred over. I called on May 4th to fix this issue, after several transfers and waiting 2 plus hours, I was told the issue would be resolved.

A couple of weeks later, I realized my Apple care had still not transferred over, so I called Apple again on June 19th. Same process. Waited hours, transferred several times between departments, and was told my issue had been resolved.

Now it’s been several months, and I am ready to upgrade but I can’t do so because my replacement phone is still not listed in my upgrade plan. I waited 2 hours and 22 minutes on the phone, I was transferred from department to department, with each specialist more clueless then the previous one. Finally, I reached a specialist that said he would create a case that will be need analysied by a different department and take minimum of 3 days. This is exactly the solution i was told before and it never fixed anything!!!!

honestly, Apple customer service has been completely useless and they can’t fix a simple thing. Is there any department I can complain to? Or some way to escalate my issue? Apple has no problem billing me month after month for my plan, yet when they are unable or unwilling to fix/acknowledge their mistakes. If I wasn’t so invested in the Apple ecosystem, I would leave it all behind, sell the phone and switch to android. Unfortunately, I have too much invested in Apple products so I’m reaching out to anyone that may have a solution