Unethical business practice

I purchased a laser printer (Samsung ML-2510) from Buy.com one month ago. Buy.com now has third-party sellers who are small time retailers. I happened to purchase the printer from this company called Techsunny.com and when I received the printer 10 days later, I found out that it did not work. I asked for my money back; I called and emailed several times. The service rep, Ricky, was very rude and initially refuse to refund my money. Then he tried to charge me a 15% restocking fee. The printer was defective!! When I disputed the charge with AMEX, Techsunny agreed to giving a full refund. It still did not reimburse me for the cost of shipping it back ($20.78). The company should not be allowed to have the customer to pay for shipping cost when the merchandise is defective.