You've got to be kidding. First, the definition of KEY employees must be checked. I find it VERY hard to believe a 401(k) plan which passes ADP and has 200 eligible ees to be T/H! (Unless there are a lot of family members!!)
Second, I think the bank fulfilled its obligation barring some special contract features. The Plan Administrator failed.
Third, if it were our plan, we would have accrued the TH contribution regardless of what the client wants, because it is required to be paid. It would not 'disappear'.
Fourth, what is this bit about 'correcting' the TH problem?
Now the bank knows why you hire TPAs.