We found Chase in Canada (I can't speak for them in the US) to be quite lacking in responsiveness. I was pretty surprised about it actually.
We're going with Optimal Payments up here (www.optimalpayments.ca), who have been very responsive, amazingly helpful, and have really good rates for Canada too :)
Chase has excellent rates and amazing customer service. I've tried many Merchants and they're by far the best I've ever used.