When we first took them on, we had a payment issue with them just one time; they were very responsive, and resolved the matter quickly.  A computer malfunction on their end.  Other than that, we've had no problems.  They're demanding, but they send us a good bit of work, and at this writing, their account with us is current.

Wayne Schutt, their marketing guy, is a personal friend of mine.  Contact him directly, and tell him you saw this post on SOT...he'll square you away.

Regards,
Scott Perry