MrAnnuity

Reach out to whoever brokered the annuity. While ultimately the plan sponsor's responsibility to make sure all benefits are preserved, they rely on the broker to do this on their behalf. The broker is in between the insurance company and the plan/participants and should be able to address/get this fixed if needed.

I third the consultation of the ERISA counsel. That being said, I have seen this once before. The annuity contract did not contain the COLA and everything passed just fine. Another consideration is valuing this feature for lump sum calculations.