I have been using Simtech Development for a long time now to do all my cart improvements. I used to have different shopping cart and hired some "experts" on freelancer site to do some improvements specific to my business. Unfortunately after paying for such changes, I would find out that suddenly some other parts of shopping cart are not working correctly. Of course the "experts" say it's not them, so I had to hire some other "experts" to fix the changes I have already paid for. My shopping cart was so messed up that I stopped getting orders and I had to simply start over.
I started with Cs-cart and I have been happy ever since. It comes with MANY features, but if you are missing some specific ones, Simtech Dev can do it for you. I have had over 20 new modules installed. At this point my store www.RedLeafTea.com offers the largest, customizable green tea selection. My flavored matcha teas offer over 250 ways to customize your green tea powder. This would not be possible to do without changes that were done by Simtech Dev.
Did I mention they guarantee the work for 3 months in case you find out some issues with it later on? The person I have been working on from the beginning is Andrew Golobokov and I could not say enough nice things about him and his work. The best part of this is that they are the REAL experts and I have a piece of mind that it will all work. I have NEVER had any problems with communication or the work they did.
Trust me, they come HIGHLY recommended.