First time writers seeking literary agents are often unaware that legitimate literary agents do not charge reading fees or so-called "processing fees."
Dave Kuzminski of Predators and Editors says it best:
Legitimate agents do not charge reading fees. Their own organization bans those. What makes you more of an expert than the agents themselves when it comes to such fees?
Furthermore, what you paid for is a critique. However, critiques are subjective because those depend strongly on the individual preferences of the critiquer. You could get a dozen such critiques pointing out problems with your manuscript and still get represented by a legitimate agent and even published by a legitimate publisher because it may still be marketable in their opinion. Likewise, you could get a dozen such critiques that gush over your manuscript, but still get rejected simply because there are other manuscripts just slightly better or more marketable in the opinion of those doing the representing or buying.
Send your work to agents who don't charge reading fees. I think you'll find that you stand a better chance that way then trying to rewrite your manuscript to match what one critique suggested only to be disappointed later when you discover that you're trying to make one size fit all when in publishing it can't.
Remember, your objective should be gaining acceptances, not rejections.