I understand how challenging this situation is regarding the reactivation process of your perpetual license for QuickBooks Desktop 2020 Premier Accountant, Yiadom.
You are experiencing issues activating your QuickBooks Desktop because it has been discontinued in the UK. As a result, all QuickBooks Desktop services, including support, online activation, and live services, have officially been shut down in the UK.
Also, when your software tries to verify your license using the QB Tool Hub, the Error 3371 issue occurs. It indicates a failure to connect to Intuit's servers, resulting in the error message: "Navigation to the webpage was canceled," which prevents the activation process from completing.
Since the desktop version of QuickBooks is no longer offered in your region, you'll want to switch to the QuickBooks Online version or use a third-party application.
We'll be here to support you again if you have follow-up concerns.