Instead of getting a free domain name is it possible the credit towards my account?

I really don't need another domain name.

Sorry, we don't issue any credits if you already own domain names

sorry what I mean is, I don't want to have hostony register another domain name for me (I've got too many). I'm guessing this domain name would count as one of the domains that I have hosted and I don't want to have domain hosted that I don't need.

If I change the DNS records for one of my domain names and point it to Hostony, will Hostony credit my hosting account the cost of the domain name that you would normally register for me?

Soryy, no. Free domain name is a option for the newbies who need domain name.
We don't provide credits to those who already have the one.

what happens if I don't want a domain name?

We can transfer it to our registrar or do nothing.
We can register or transfer domain name if you need it.
But if you need not a domain tranfer or registration we don't credit it.