Wow, that's a tough position to be in. I cannot recommend TalentPop.co highly enough. These guys got us up and running in 2 weeks with trained customer service reps and their own internal management team. We've had some really amazing staff that we selected through them in the past during peak seasons when things get intense. Their cost starts at $8/hour and I'm pretty sure everything they do is month to month, so you can start with a big team then shrink the team size down once your caught up. Good luck!
