I have a strange question... I purchased a 15" $2,399 Macbook Pro. However, I'm still within my return window and I've decided to exchange it for the 13" model since I prefer the smaller form factor and the 15" specs are overkill for me. So, my question is for those of you who exchanged for a cheaper model... Did they simply refund the difference on the spot or do a full refund of the more expensive model and then allow you to buy the cheaper model? The reason why I ask is that the card I used to purchase the 15" has a limit of $4,000 and refunds take up to 48 hours to process on this card. So if they do a full refund then I'll have to wait a couple of days to go back and buy the 13" with that card. However, if they simply refund the difference between the two on the spot then I can get the whole process done in one shot. Thanks for your input!