Where is your traffic coming from? this is the first thing to know. The better the quality of traffic the morelikely it will convert.
You are using Zen cart which is SEo friendly out of the box, but it looks like you have had a weird modification done to it that I can't quite work out the logic behind. (or is it an error in the coding?)
From the front page, I select an item, but the page I get taken to has a completely different image on it, with the item I want below it. this is a MAJOR LEAGUE screw up When people click on an item they EXPECT to see larger images and more information about THAT item, not to be presented with a large image of something else. I clicked on the Black cat image and was presented with a purple witch. I had to look around the page to find the information I was looking for. Most people will assume it is broken and that the links are going to the wrong page, and they will leave.
Who suggested you do what you are doing? If it was you, then swallow your pride and remove it, if it was your SEO/web designer, find another one as they are costing you money.
The main question though will still be where is your traffic coming from?