Its probably not my place to comment here, but the Dealer has an obligation to work with you to resolve this issue.
JBJ tanks cracking, although not uncommon, is not really rampant in the product line. They sell thousands of units and when things do go bad, forum users usually post and take note.
I would try with JBJ. If the crack seems to come from the corner where the glass is bent, its usually a claim that can be honored, since its well understood that that is a large source of stress.
As for me. When a customer of mine has a cracked tank, i will generally advise them of the following:
1. Immediately start dialogue between yourself and JBJ, explain where you bought it from.
2. Contact the vendor to let them know that you have a claim under review with JBJ.
3. The dealer should then contact JBJ and keep them appriased of the situation, and get authorization to replace the product for you.
4. You go back to being a happy camper, and the dealer and JBJ work something out.
In my experiences ive shipped close to a few hundred units, and have had maybe 10 go bad.
In most cases, I was able to coordinate with JBJ to get the customer in a replacement unit.
The settling part is fun fun fun for me. lol. but i think that its my responsibility to my customers.
My advice is to try again with the dealer. They have it in their best interest to serve you too.
hope this helps,