I will paying off my existing one. Then starting fresh new one.
If you’ve paid 10 months off you should be eligible to upgrade. Having made reservation, you go into store with your old phone and they pay off the loan there and then with that before then taking out a new loan (with credit check) for your new phone.
if you’ve not paid 10 months, then I think the alternative is to ring Barclays and pay off over the phone, so that you own it and then you can get a new agreement.