Risen seam, seller service miserable

The bag is unfortunately risen daily use at the seam after nearly 3 weeks and fell in two. But that can happen even once. Nevertheless, I want to give 2 points for the design of the bag, which really is very suitable for everyday use of the Sony Nex.

So I then contacted the seller by e-mail, described to him the event and politely asked for a replacement. Back comes an e-mail with no address, salutation and sender with the contents: Contact Amazon Customer Service, which is an FBA order.
So I wrote to the Amazon customer service, the kind pointed out to me that Amazon had no jurisdiction. So Another mail came to the seller with the note from the Amazon customer service, but again came back only the above phrase. For 2 months I have been trying to make contact to the seller almost weekly and polite, but was either not responded to my email or the above phrase has been sent. To date, no response to my request customer friendliness is another way!