Orlando advisor

Hello, I discovered that I had not filed the 5500 for a single person 401k plan for 2022 and 2023. There was a miscommunication between me and my CPA and I though he had handled it. As soon as I discovered this, i promptly filed the information returns. Then I get a letter from the IRS that I owe the maximum of $150k in penalties. Any suggestions for approaching this with the government? Many thanks.