You may be blaming the wrong persons. TEBs are NOT limited to 15 characters. More like 250 or so.
Can you be more specific about where you are seeing this 15 character limit evidenced?
Are you sure you're not just seeing 15 characters when you insert the TEB variable into a text box or something? Did you perhaps insert a variable to display by simply adding dollar signs to the ends of the variable name rather than using the Insert Variable dialog box? If so, that would explain your 15 character limit. Inserting variables this way doesn't give you the option to set the variable display length. That's why you should always use the dialog.