Barclays loan balance not updated after iPhone trade-in at Apple Store

i traded in my iphone in store to end my barclays loan agreement for the iphone upgrade program. i didn’t re-upgrade. I just traded my phone in, and they gave me the option to use it to clear the balance at Barclays. i have a receipt saying i the balance was paid off. how long will it take for this to be updated with barclays? as they have just taken a payment even though it was paid off at the Apple Store. Therefore I’ve just overpaid.

[Re-Titled by Moderator]

Original Title: Barclays loan agreement paid off in store but not reflected on my loan balance with Barclays.