You should definitely contact support if you don't think you've been credited properly.
Do you have access to the date that the erroneous charge posted to your account? It seems to be the case that in many cases, Dreamhost has issued the credit through your credit card, but as with all banking transactions, the inevitable/normal delay in posting applies. Checking with your bank or credit card issuer may also provide some additional information, as they can often see credits that haven't posted yet.
What are [color=#CC0000]50DISK50[/color], [color=#CC0000]3DOM50[/color], and [color=#CC0000]1IP1DOM50[/color]?
They're Dreamhost coupons!