FillPDF not displaying 'foreign' characters

I'm using the fillpdf module with the online FillPDF service to render the PDFs. Most everything is working great; however, if a database field I'm displaying on the PDF contains certain 'foreign' characters, those characters don't display at all.

Notably, this occurs with the circumflex (ĉ) and caron (č) characters. Other foreign chars display fine (eg ö, é, è ...).

Not sure if this is an issue with the FillPDF Online service or the way our database is configured. Everything displays correctly elsewhere - ie. on our website, printed documents Etc.

Anyone got any ideas? P

Update: turns out that the characters that don't print are NOT in the extended ASCII character set. The 'foreign' chars that do print are in the extended ASCII char. set. I'm not sure if this is an issue with the fillPDF online service or with XMLRPC (which is used to send data to/from the service). Not sure there's any way around this...