Changing (Lanes) iPhone Upgrade Programme UK

I played out two scenarios to get on to the iPhone Upgrade Programme UK as the reservation system for the Upgrade Programme simply does not work as it should.

Apple retail have this term called changing lanes which allows the customer to change the method of payment when getting a item.

Scenario 1 - Ordered iPhone X online on release day, delivered to home address. I took it into Apple Store wanting to move over to the Upgrade Programme. after an hour of employees trying to find the right process to do this, i'm told that this wont be able to be done without losing the current iPhone. One return is processed the serial number automatically gets assigned to the next person waiting. There is no way of Apple holding the phone to change to Upgrade programme which would take only some minutes. A big disappointment.

Scenario 2 - Ordered iPhone X online on 6AM to collect in store the same day. Got into store to collect telling Apple employee what I want to do getting the response 'of course we can do that'. then employee confirms with management that in fact it cant be done even though the payment has not been processed as I have not picked it up yet. The iPhone once returned cant be put on to the Upgrade Programme straight away apparently. A big disappointment considering I done this last year without an issue.

Any clarification on this as Apple staff don't have a clear idea on how to do this.

Anyone experienced something similar?