Distributions from Vanguard

I have a terminating Defined Benefit Plan with assets in a pooled account at Vanguard.  I prepared my standard Letters of Authorization for the Trustee to sign and submit to Vanguard for the benefit payments.  Vanguard said the Letters were not sufficient but did not provide any alternative.

Does anyone have a form or template that they have successfully used to get payments made from a qualified plan with Vanguard?

Thanks,

We had an incredibly difficult time with them last year. They were requiring medallion guarantees, etc.

Client finally opened an account at a local bank and the trustee was able to go online and request a wire to an account "with the same name". Paid everyone out from that account.