Bit of a mystery this one - our logs show the blockchain connection as healthy. We've refunded the money anyway:

https://blockchain.info/tx/7fc15a8a15448d1cb7d4bc735faf0552fda121e0cbe7b6f63f427cd56a26e995

We'll monitor this thread for any more problems.

OP: If you'd kindly add [solved] to the title when you get the chance, we'd be grateful!