In 2017 I signed up for Medicare Parts A and B, Aetna Supplement Plan G, and XYZ Part D prescription plan. My Aetna started at $137/month and it’s now $226. My Part D premium has also increased. Is it possible to switch to another carrier at this time and/or change to plan N? How about switching from XYZ Part D to a better prescription plan? My meds are Lovastatin, Lisinopril, and Levothyroxine. I’m not interested in an Advantage Plan.