We had a problem with cogent about a year ago. Somehow.. cymru was
announcing a /32 of ours and black holing it for whatever reason. It
was removed but wasn't happy that cogent was allowing cymru to do this
sort of action. To this date we do not have a valid reason from cogent
on why they allowed this to happen.
Of course, if it was accidental, then there wouldn't be a "valid reason"
why "they allowed."
It could be more helpful to indicate what they did tell you.