There are rumors that the XROST link is removed for those logging in from US-based IP addresses. What's odd is that I can still see the XROST link, but my friend can't--and we're both on the same ISP!

Nonetheless, after some Google'ing, someone posted the link to redeem XROST PIN codes.

https://ssl.allofmp3.com/pays/paymen...tep2&via=xrost

I sent that to my friend, and he was able to refill his balance.