Went to Stratford this afternoon on a whim with no reservation.
They seemed to have plenty of stock, so started the iUP upgrade process from my XS to a 11 Pro MG, but was rejected by Barclays. I recently moved, and updated my address everywhere accept with them. Gave them a call and was told that is why it failed. I have great credit otherwise, so pretty disapointed.
I've confirmed that my address with Barclays and Experian are both correct, so now plan on heading in when the store opens tomorrow to try again.