I bought a 6 pack-cell (for $450 + shipping) on eBay in April and this thing stopped working in August. I contacted the seller and he promiced to replace it if I ship it back to him. Which I did two months ago. And until now he didn't replace it. He just stopped answering my emails. If it possible to make him to replace it or refund me my money? I would appreciate anyone's advice in this matter. Thank you.