Ash was catnapper, i remember spending an hour or more trying to settl her just to get 30-40mins from her.
I can't help much on how to settle in cot cause we would either use the bouncer or pram to get her to sleep.
Maybe as Trish said try Hammock? I have heard good things bout using one, some places do hire them out.
I'd say once he sorts out day sleeps better he'll prolly settle alot better at night.