Legal Question in Credit and Debt Law in Michigan

The short answer is that what you call a "letter of Undue burden" is probably not going to excuse your appearance.

A more complete answer requires more information. An answer is more of an exercise in helping you to identify and understand your options.

First question is which court issued the subpoena? That will enable us to determine which court rules apply, whether the court has jurisdiction over you, and the rules which apply to an objection to the subpoena.

Second question is whether the subpoena was properly served. If not, you might want to nevertheless consider compliance because being held in contempt of court, even wrongfully, may be inconvenient.

I would need to see the actual subpoena before giving advice to a client on his or her options with respect to it.