InksOutlet InksOutlet.com, Returned faulty merchandise with RMA and they repeatedly promise refund but don't deliver gilroy, California

July 2010-bought Epson ink cartridges but the didn't work; sent email to resolved the matter but no reply; called a week later and Jack promised to email a return material authorization form - which he did.
I shipped the cartridges back a few days later, return receipt confirmed by post office; never received credit to my card
Called a couple of weeks later and they said they had received it and were going to post the credit that day.
Called a few weeks later and they said "it takes time to show on the statement" (yeah, right! I can see pending transactions!)
8/30/10 I called again and spoke to Jack; he said they would credit 51.27 to my acct today.
It is now July and I have never received a refund even though I returned the faulty goods months ago.