unlimited space in theory is not possible on any server (to be honest)
512 MB has been a standard size on all new accounts for a while.
even 512 is a big chunk of space for your typical website,
considering your not allowed to store files that are not used.
(as per the terms of a free account)
if you actually do need/use 512 MB for a website (still a lot of space)
they provide the option to increase it then.
so even if your only using 250 MB its still pointless to increase it yet.
this is just an opinion.
however if you still want an increase it may take time for a staff member
to see your request so dont expect instant replies for free accounts.
when premium users are the priority for assistance.
some issues go unseen by x10 staff for weeks or more.
you can try requesting through the
https://x10hosting.com/contact-us section of the website.
you may get better/faster results for some things.
the forum support is mostly based on volunteer help,
and volunteer's dont have that kind of access.