I too spent an hour on the phone this morning and when my call ended I felt pretty confident the agent understood the issue and the larger implications for all those who are about to discover these incorrect W2 forms.

My agent opened a case for me for a W2 correction and had me upload the retirement plan summary and payroll summary that showed the total deferred in the original SIMPLE IRA deduction item and the total deferred in the SIMPLE IRA Higher Limit deduction item.  On the report I noted that the higher limit total should be added to the amount in Box 12 Code S.  

I later got a call from payroll corrections team.  This agent was far more difficult to communicate with but after answering the same question 5 times I hope they will correct it.  She kept asking me for the year to date total in SIMPLE IRA and annual limit which I repeated was $17,600 for me.