Easy solutions:

1. refund money.

2. replace all defective goods


Regardless of manufacturer defect, seller mistakes or both, seller should be responsible for the defect of goods sold. Refuse to replace all defective goods is a breach of verbal contract between seller and buyer.

I wonder why moderators or trade enforcers do not take action or at least help in solving the case.

To buyer: you reserved the right to be angry. Since seller has no intention of replacing ALL defective goods, this is considered misconduct of business ethics. You should reveal all his/her details ie. bank account etc.

To seller: regardless of you being a middleman, reseller, direct seller or manufacturer. You are the one in contact with buyer make you responsible for all problems arise from seller side.