I can no longer create addon domains

[Salvatos]

Hi, this is an issue that has been going on for a few months. When I try to add an addon domain through cPanel (I've tried different names), I always get the following error:
Sorry, you can not add a DNS record for a subdomain of another user’s domain.

The domains I've tried were in the format name.x10.mx and I've checked that they weren't already in use by other users. The error message leads me to think I can't make an addon domain directly under x10.mx, but I already have three of those on my account (or rather had until I removed one to make a new one)... And if I try to make name.salvatos.x10.mx, I get:
You cannot park a domain on top of itself.

Am I doing something wrong or is this broken? I have no idea what server I am on anymore since cPanel doesn't say and when I try to check in the Client Area it's been saying "We're currently updating our client area, some functionality may not work for the next few hours." for the past couple days.

 

[Salvatos]

E-mailed support two days ago, no reply.

Tried switching themes in cPanel, now I'm stuck on the Basic theme where half the links lead to blank pages and I can't switch back because it just logs me out, so now I can't even properly manage my site.

Does anyone still work at x10 or are the servers just running on their own until they crash? The amount of dead links and broken features, and the lack of activity for the past two years, aren't looking good...