There is another post specifically talking about what it takes to get a Silver account now.
It seems people were getting varied results, some of the factors are:
1) paying for subs with CC or Krono
2) buying something while subbed (the biggest thing people spoke about was purchasing the ability to use RK II spells as silver, which I did not know you could do)
3) Age of the account.
It seems the ability to actually revert to Silver from Gold instead of reverting to Bronze was kinda all over.
I have one Gold (pay with CC) and a Silver that was silver from WAY back in the day when they first offered it, I have access to general on my Gold. My only recommendation is maybe farm a krono, or flat out pay for a month of EQ, and then if you can buy something off the DBC store like maybe buy another 500 DBC, then see what happens when the krono expires.