Hey mate, currently that's not possible. The processes are handled completely differently so to upgrade you need to use the upgrade page. Credits are currently only for running premium bots.
I believe there is currently an RS Gold site that advertises here that allows you to buy RSGP in exchange for RS Gold, but that's more or @Arbiter's domain so he would know better than I
I can try to manually exchange the two. How many credits would you like to put towards upgrading your account?
