OK, I still don't see you coming back into the chat here. I'll assume that you have not provided the needed documentation.
If you'll look at page 7 of this document: https://www.ssa.gov/pubs/EN-05-10536.pdf (Medicare Premiums: Rules For Higher-Income Beneficiaries), you'll see that SSA provides a way for you to document that your gross income has gone down.
From there (I'll underline the pertinent part):
"If your income has gone down due to any of the following situations, and the change makes a difference in the income level we consider, contact us to explain that you have new information and may need a new decision about your income-related monthly adjustment amount:
• You married, divorced, or became widowed;
• You or your spouse stopped working or reduced your work hours;
• You or your spouse lost income-producing property because of a disaster or other event beyond your control;
• You or your spouse experienced a scheduled cessation, termination, or reorganization of an employer’s pension plan; or
• You or your spouse received a settlement from an employer or former employer because of the employer’s closure, bankruptcy, or reorganization.
If any of the above applies to you, we need to see documentation verifying the event and the reduction in your income. The documentation you provide should relate to the event and may include a death certificate, a letter from your employer about your retirement, or something similar. If you filed a federal income tax return for the year in question, you need to show us your signed copy of the return