Years ago there you could arrange an in person talk with an agent at the local IRS office. If you are near any major city they probably have an office there. If you can not get through on a phone to make an appointment now-days, you might have to stop by to make an appointment in person if there is still an opened office. That would be 2 trips, but after you do sit down with an agent they will process everything to correct any problem providing you bring everything you should.
Years ago I did that once down-town Pittsburgh PA. I have not had to do that for a long time, so I do not know how that would go now-days.