Automatic Enrollment - notice not provided

I'm having difficulty finding any guidance on this - we have a 401(k) plan with an automatic enrollment provision (ACA) and the client did not provide the required notice for the past two years.  They have been operating according to the provisions in the plan document, they just neglected to provide their employees with the notice.

Is there a "correction" for this?  Maybe anyone that was auto enrolled would need to be given the option to remove their funds?

I'm not aware of anything, even informal, on that exact topic.  The IRS website informal guidance on correcting a late safe harbor notice is probably the closest thing available. The fix described for the late SH notice varies by person depending on the impact of the late notice on that person.

https://www.irs.gov/retirement-plans/fixing-common-plan-mistakes-failure-to-provide-a-safe-harbor-401k-plan-notice

I think part of the picture would be how much information the affected participants were given about the automatic enrollment. Were these participants given an SPD that described the automatic enrollment?  What about enrollment forms? 

I don't think you would be able to allow them to remove deferrals, other than during the limited time period allowed by the regs.

Anyone else have any suggestions?