My phone no longer has service with a provider. I tried to unlock it with my former provider and they said they couldn’t unlock it because it was purchased and activated at an Apple Store

Your former provider is giving you the runaround. Only the provider can unlock the phone. Apple is not a provider.

Ask for a senior support person at your provider who will give you some straight answers. Please note that they may be under no obligation to unlock the phone.

Acerdude wrote:

My former provider can’t unlock my phone because it was purchased and activated at an Apple Store.

Phone can only be carrier unlock by the phone carrier it is locked to as outlined here How to unlock your iPhone for use with a different carrier - Apple Support