Looking for a Recommended PPC management Firm

Good afternoon,

My company is currently looking to outsource the management of our pay-per-click campaign. We previously had another third-party PPC management company take charge of a moderately successful AdWords campaign; however, we were not entirely satisfied with the results.

This time around, we are hoping to find a company that was referred to us and we're trying to get as much feedback as possible. If anyone has had a positive experience with a PPC management company, I would greatly appreciate hearing about it.

FYI - (We are an ecommerce / catalog-based wholesale company with markets in the U.S., Canada, and the U.K.)

We are looking for the following (somewhat obvious) qualifications:

-Delivers excellent results - a good track record; referrals, client testimonials etc.
-Preferably Medium-sized company with a large enough qualified staff to handle a medium-sized campaign.
-(a large company only if their services are extremely superior and they offer good rates. We don't want someone who will "manage the campaign" but will not take the time to optimize it).
- Reasonable Pricing Structure.
-Located in Canada or the U.S.

Many thanks in advance for all your feedback!

-Jen