If Mojang support can't help you, your only option is to buy another account. Sucks, but Mojang is the only entity with access to your information.
We can't deny there are illegal options to get accounts, but
1)we aren't going to tell you about them
2)they're illegal (such things are usually stolen)
4)the person you obtained the account from can simply call Mojang and take the account away, and Mojang will happily help them do it (after all, they own the account).
5)dealing with stolen goods/information can result in your legit holdings being banned/blocked/seized/etc even if you were unaware of their stolen status. Will you go to jail? For intangible stuff like account access, probably not. But Mojang could cross-reference your current information and find additional accounts legitimately in your name and decide to ban those too even if they weren't questionable in nature.