WTF is anyone paying?
I mean, let's assume the decryption works, and is faster than restoring your backups - both really long shots.
There's no way you can't possibly actually trust any of the data you "get back" anyway.
They could - and almost certainly did - put further unwelcome surprises in there. Or change a few important numbers - it's not like spotting "things that look like bank details" is hard, for example.