Recovering a RS account

As the title states, does anyone have any idea how to do this?

I haven't played in about two years but a buddy of mine DM'd me that I was online and sure enough the account somehow seems to have been hacked even despite literally only one person here in the community ever even knowing the info (doubt it's them though, seems very random being multiple years later and I can't even recover it with all the info and they only know a single PW/Username).

I literally have a little book with all the information written in it but that fucking automated system Jagex has for the recovery system denies it everytime within seconds.

Any alternatives to this garbage system they have applied?