I am not entirely sure, but it would seem like the ME sim part is lost.
What I take into account to say this :
The easiest way to find the information I'm looking for is simply the exam registration form.
Among the list of required documents, you will find one document where the ATO needs to certify that you have successfully attended an approved training programme.
This is because the authorities consider that your piloting level is guaranteed not only via a test, but also with a training that follows an approved training programme.
This approved training needs to be followed entirely.
If you only did the flying part at ATO B, they would not be able to certify that you did the sim part at ATO A.
Imho, you have little hope, but still some hope, still the ATO is taking responsibility for this document. You could find an ATO, and convince them to sign the document telling you followed the approved training programme.. Since you attended training elsewhere, you can always ask another ATO to sign this document, and hope they will accept.
If they accept, you can probably acquire your license. It will however be in an unorthodox way.