Why Didn’t My Plan Change?

I enrolled by the deadline, and then changed my plan from a bronze to a silver plan by the Feb. 14th deadline. I went through all of the steps to make this specific change twice, but could see no result of it. Now I am still enrolled in the wrong plan which is useless to me. Why did it not work. I need to see a doctor immediately and was relying on next months coverage which I will not receive.