Anyway I personally think buyer should be responsible cause he sold it saying it s478 which it isn't.

Buyer: From what I understand, it's your fault not checking thoroughly before buying.

Seller: From my experience, no point being so defensive on what you think it's right. Sometimes what's right doesn't means good. Since you are in the "business", it's good to have one additional friend then having half an enemy, because when they spread the news, it can be thousand times inaccurate. No point curing a problem when u can prevent it from happening.

If you think refunding is not an option, why not do an exchange, but charge him 10-20% premium for the thing the seller needs. Always find win-win solution. And you are looking for a long term business, sometimes you need to loose a couple hundreds to earn back a few thousands.. You know that!!

Buyer: THINK before you BUY!