Wow, typical repair shop. They have no idea what they're doing and remove the OS restore partition. You have no idea how many times I've seen this.

Anyway, it appears a manual reinstallation is required (thanks, repair shop). Since the MD partition is still there, this shouldn't be too hard.
http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?docid=179256

Removing bitlocker is not hard. You do not need the diagnostic partition. The diagnostics can be run from the resource disc or a flash drive.