One more thing ... when you send the document, if it is your preapproved document, be sure to remind them that they cannot rely upon you anymore to keep the plan up to date. That will let them know that they must amend onto another document (and if the "new" TPA doesn't have one, it will highlight that. Second, when they get nailed by the IRS for having their plan out of compliance, and they come crying back to you, you will have proof that you advised them that you don't do that anymore for them.
FWIW.
Ilene