woud personaly learn from it and move on.
have had a similar sort of situation with the first flock of mine though there wasnt any payment and am still glad to have the little buggers and woudnt give them back for anything.

the lad had got the hatching eggs off for free [because knew him and used to walk his dog] bred marans and light sussex mainly.
he didnt say they were inbreeding though,was only told that after they were born with complications.
lorna turned out to have a crippled toe and is a bit mentaly impaired,and kanner;the cuckoo maran was born far to small and he developed serious intestinal shedding through cocciodosis either during incubation or just after hatching,he was lucky to be here but he is now the biggest cock,he is also very agressive and has been since he was a nipper [excuse the pun, nipper also means slang for child here] and he badly molests the poor hens but gets on well with the other cock tito,have had a feeling the inbreeding is the cause of his agresion.
woud say to count this as experience,at least have got a fair idea of some signs to avoid now,and can also warn other people of what he is doing though watch out for getting threatened with slander which guilty people usualy do when they havent got any other defense.
if he is on any chicken purebred breeder websites; contact them to make sure he gets taken off the lists.
is getting a lawyer an interest? they coud write a letter which woud likely get a better response out of them but it obviously woud mean spending more money which coud be put towards those chickies or some more chickens perhaps.