Hi Popmatin,
Hearing what you've had to say it sounds like you're experiencing an identical situation to myself - did you apply for finance using a different shipping and billing address? Do the two addresses you gave match identically?
My situation initially was that I was waiting a long time for my order with Apple to change from 'Awaiting Payment'. Each time I called a representative I was told it would be fine in 24 hours - what had actually happened was Barclay finance mistakenly approved the loan application when it had actually been declined, but never told me otherwise. Further discussion with Barclays uncovered the fact that the Apple people I spoke with who claimed to contact them never actually had, and this is an issue I still need to take up with their customer services.
What you need to do is call Barclays Partner Finance. An Apple representative will give you their number and have your Loan ID/Approval number at the ready. You'll be asked when you call them for a 16 digit number but either ignore this and wait to be put through or put in approval number that you've been given. You'll be put through a representative and they will ask for everything all over again! After all of that, Ask for the status of the loan and whether it has gone through. Your order ultimately rests on Barclays transferring funds to Apple. From what I've been able to gather, communication between these two companies is useless. Representatives don't call Barclays regarding questions about your loan, they email them. Barclays take at least 3 days to respond via this method. So they practically invite delays into the whole process. Anyway... call Barclays. Once you've established the status of your loan, they should be able to contact their underwriters and advise what the problem is.
After I contacted Barclays, they realised that the loan had been approved in error (it should have been declined because my shipping and billing address were different), acknowledged they were at fault for doing this and compensated me. Once I re-applied for the loan (after they removed my other loan applications from my credit history) it was approved and I had the iPad delivered within days.
Hope it all works out ok for you.
Good luck!