Owe taxes from 2023

I received notification in January that the irs had reviewed my taxes from 2023 and that I had underreported income. I thought all that taxes had been claimed but it was off by a little bit. Also, I had a debt forgiven and dont even remember receiving anything IRS related on that. I immediately upon receiving the notice agreed to the amount. I then filed my 2025 returns. I have tried calling the IRS payment line for months no answer, it says too high call volume to take my call. I was supposed to get a tax refund but my transcript has showed additional action pending since March. Any suggestions?