i was overpaid all in cash miles. But because I redeemed some cash miles, I didn't have cash miles when they took the over mat back, so they too all cash miles and some dream miles to make up the difference. I wonder what would happen if I redeemed all cash miles before they took the over payment back. Would I have a negative balance? it happened to my HBC reward acct when I returned something after I earned and redeemed the HBC points. My HBC reward acct has a negative balance. So I just got another HBC reward card and throw away the first one that had a negative balance.