Credit card processor for magento advice and instalation need it

Currently I am using on my website Paypal advanced for processing credit card payments. Over 25-45 % of the payments per month now are being rejected. Every time I call paypal they say it's not their fault, it's the buyer's bank fault. How can this happen...from so many different countries. I've been reading around and some people are saying that is paypal fault. Despite that fact...I need somebody to help me choose a new credit card payment processor and to install it on my website, which is a ecommerce magento store. I need an expert, who will explain his choice and knows how to avoid the rejected payments. I prefer somebody with experience in this area and again somebody who knows what I am talking about.