Take my review in consideration before doing business with those scammers (for your safety!). officialiphoneunlock.co.uk
"We attempted to deliver your unlock Over The Air via 3G and Wifi, but were unable to do so. We respectfully have to inform you that your iPhone... locked to T-Mobile USA is unfortunately marked by the carrier as Barred/Blocked... As we have already prepared your unlock and incurred the unlocking charge, we cannot supply a refund for handsets which are rejected in such circumstances."
You will never get Refund from their end.