That’s a shame that they won’t cut the storage costs. But I can’t really comment on their fees. I just know that they are probably the longest established and most reliable FBA prep type services around. I used them for my first few years and they helped me when I got in difficulty often.
Unfortunately for you, the patent infringement issue has placed you in a tough spot which is difficult and costly to get out of. You just need to grit you teeth and persevere. Before you know it, this will be a thing of the past and hopefully things will be smooth sailing again.