Havent seen refund in 2 months

Ill try to keep this short - I received a laptop that had a white screen after a day. I returned the laptop but have yet to receive my refund.It has been about 2 months. The rep has said everything from "we sent the refund" (I contacted Paypal and they said no refund has come through from Dell... I can show my Paypal history too). I was told at one point that there was an "error" and that I should see my money in 24-48 hours... $750 is a lot of money to be floating around out there, especially in these times. I have been as patient as I can be but this is just flat out unacceptable. Im at my wits end and am praying someone can help me get my money back.