How do I sign my return without my AGI from last year?

I had to a 1040X on my previous years return. Despite me going to H&R Block for professional help, there was still apparently an error. Many months later, I received a letter from the IRS stating I owed. Called the number on the letter, and was told the IRS actually made a mistake and to fax some information in. I did that, and I'm waiting. I was told it would take 4-6 weeks to reopen and review the case. The problem is I cannot file my current years return without last years AGI and in 4-6 weeks, the already extended filling deadline will have passed.