Query problem with username

[tbworld]

But the snag, or I would have it by now myself, the file that fills $username is encoded so that file can not be changed.

Is this a vbulletin page calling a vbulletin template or an external page calling their own type of mixed php/html template?

Is the outputting of the template encoded? (Not the template)
Can you parse the output $username in php to extract the data you need for your query?

Trying to understand a little further. Not all the questions I asked above will make sense
under your code condition, but it will let me fill in the gaps of information.