Question about Premium Increase

Hello. In December 2024 I enrolled in health insurance with United Health care through my employer during open enrollment. Benefits were to begin 1/1/2025 and my premium was to be $54.44. I noticed on my recent paycheck that my premium had more than doubled. I never received notice of this premium increase and only realized it had happened because my paycheck was smaller. I called them and they said the increase was because they "recalculated my information and saw an adjustment was needed." I demanded they cancel my plan as I had not agreed to this premium, and they said I wasn't allowed to cancel until the next open enrollment period with my employer in December 2025. They said they would open an appeal on my behalf and created a ticket but I’m doubtful it’s going to make a difference and they will just reiterate what they already said and not allow me any recourse. Are they allowed to do this? Do I have any options in this situations or do I just have to accept that they can charge me whatever they like and I have to accept it? I have a nearly $10,000 deductible, and don’t go to the doctor for anything outside of my yearly checkup because I can afford to pay for anything out of pocket. I’ve also stopped taking prescribed medication because I don’t want to pay for that out of pocket either, and I can get by without it. It’s crazy to me they’re allowed to do this.