Audition standalone licence response code

Hello,

I've had to reinstall OSX and with it Audition CS6 / Lightroom 6 - I have standalone versions of each, not in use on any other Mac.

Neither will work with online activation any more, but the offline activation is giving a message that my serial number is invalid instead of a response code. The serial number is valid, but how do I persuade Adobe that it is?

Does anyone know how I can get the request/response codes to work again? I'm using https://aoes-stage.licensingstack.com/aoes/aoes/v1/IMSLogin as instructed.

Adobe told me they can't support the perpetual products by phone so to post on here and request developer / community help to resolve the problem, though it seems to me the change is at the account/server side in that Adobe has flagged these older licences as no longer valid somehow.

Any help much appreciated! Thanks.