Good to see that Mojang did in fact help you in this case. It's really hard to convince them sometimes, especially when the account is worth something Mojang tends to be more careful changing the email adress.
In my case I actually had my account permanently locked (assuming on the response I got each time) but after a while the issue got resolved after 1 year. The reason it got locked is because I went spamming mojang support with the same transaction ID on different emails which caused Mojang support to think it was a compromised account.
Thankfully got it back after a while.
This all happened back in 2018 and I have no clue how it got unlocked, it just got unlocked after I sent a mail they said "your account shouldn't have any issues to log in. (Mojang support is very odd...)
Thanks for reading.