OP,
At least ask where the bike is? Get an address. You can advise the mechanic, you understand he's busy but, he's had enough time. If it's not entirely fixed, advise them you just want the bike and will deal with anything else afterwards. You should be able to get a time and date to arrange picking up the bike.
Once you have the response, (voice mail, text etc.) and you're still getting the run around, then begin civil action. You'll have all the coorespondence of how you tried to arrange return of the bike and the mechanic failed on their part.