Lets get this straight.
You're a Platinum Seller?
You use the +2% Gallery Listing for all your listings?
All your listings are in correct categories?
CS has confirmed your Selling Settings are correct?
I'm not an expert but to me it looks like you fulfil all the conditions to be able to use:
Integrated checkout.
Up-load to GS.
If you can answer "Yes" to all the four above questions, if it were me in your position, I would open another ticket with Support on the same issues with a Header "Why am I not getting what I've paid for?".
They should be able to determine why you aren't, tell you why not and how to solve the problem. That's what Support is for.
It may be that the fault is with the way your account is set up. In which case they should be able to see your error. It may be that ebid is at fault in which case they should be able to see what is wrong at their end.
IMO, in either case it is wrong that you should be left without any explanation of what is wrong and without any way to get your account fully functioning again.
You shouldn't be left "feeling like a bit of a nuisance" because you have an account that is not fully functional.