Dukdalf Chair Spare Parts

Help needed!!

Bought a couple of Dukdalf chairs in France several years ago and a part of one of them has now come adrift.    It will be easily reassembled except for the fact that one small part is missing.       Where can I get spares for this chair?.       Dukdalf website does not list any UK suppliers and there is no means shown for contacting them direct.    Anybody out there found a source for spares or a functioning Email address for Dukdalf?