Thank you for your advice.
I have asked support to change the email back to the original one used to create the wallet. I'm not sure they will as nothing has been easy so far and they seem to have no trace of this email address.
I'm being pessimistic but if I ever do get access to my wallet I suspect the contents will be gone ;-(
If someone has changed the email address they surely they would have had access.
I have no doubt that if you previously sent confirmation of your email address when registering your wallet in Blockchain.info / Blockchain.com, then this data is probably saved. This is due to the fact that this service publicly states in its service documents that data backup is carried out in their service in the form of an archival backup copy of the Wallet.aes.json file for each new wallet.
So they definitely have your email address.
Please report here on this forum thread how your problem is progressing.
I think this is important and relevant for many users, especially among old forum users.