Received an email from them after a month for the refund offer. I saw some really good reviews for the shop so I might be the only one very unfortunate with this battery issue. At least they did not abandon my issue and gave me a refund after a while. It is possible that my battery model is just too rare because my laptop is not a popular laptop, so the battery fabricated by their supplier is one off and not good.
I would emphasize that their communication and support is good. The only issue for me is the product from their supplier and maybe the product is not good because my battery is very rare.