FAA testing center
I'm an FAA rated pilot flying both single engine and commercially in Europe.
Also I'm an AF Reservist assigned to Stuttgart.
Contact Mr Hans Schaefer in Stuttgart. +491775277152
He should be able to point you in the right direction.
You could also contact the US Consulate in Frankfurt and ask for the FAA rep, he/she also may be able to help.
I'm surprised the folks at Coleman couldn't point you in the right direction. I have contemplated joining there but right now just too far to travel.
good luck,
Lifter