Well, you need to uninstall before you try to install again. If not files are removed succesfully, you may need to delete them manually.

If it's not listed in the list of Joomsef extensions how can I uninstall it? I just don't get it, if it said success why it wouldn't show in the list of installed extensions.

And what would I look for to delete them manually? Or making sure the joomsef.php is complete.

I would recommend you deleting

components/com_sef
and adminsitrator/components/com_sef

directories and then reinstalling JoomSEF.

Class 'sef_joomsef' not found just installed the sobi2 exstension for Artio joomsef

I installed through the joomsef exstension manager - however it doesnt show as being installed.
I have disabled cache on all sobi2 levels

Still not working, as this is a paid plugin I will be requiring some assistance alternatively I may have to ask for a refund as I have followed all the instructions.

Hello,

Which version of JoomSEF and SOBI2 extension have you installed? According to the error it seems you have installed an incompatible version of SOBI2 extension.

Best regards,
ARTIO Support Team

Yes I couldnt get it to work so I used the free addon from Sobi2. I disabled Joomsef. As your product didnt work I guess a refund would be a good idea?