Saint Christopher 3D print model

I gave this a positive review yesterday, but once I started prepping it for print this morning, I realised their are two extra faces added afterwards but the mesh reads as one. Once you do mesh union (I used the st christopher in a pendant with a frame), the 2 faces disappear and there is a hole in the child's face at the ear.

Paper thin, Designer responds with sarcasm. Not recommended.

This file has been opened on matrix and rhino, both updated. The file is only showing the edges of the file and not the centre detail. Please can you help me with this.

Thank you, great model