If you are not taking it with desferal, you should keep supplemental vitamin C to a minimum, if at all. If your ferritin is already quite high, it may be best to not take extra C until you get it under control, as there is too much free iron in your system and adding vitamin C can cause iron "clumping" in your heart and reduce heart function. I feel the best source of vitamin C for thals not taking it with desferal is from diet. You can eat citrus, but eat it as a snack between meals so it does not enhance iron absorption from your other foods. A mid-afternoon orange is a great idea. Even grapefruit with breakfast is OK if you are not having any iron containing foods, but this is a personal preference, so look at what you're eating before adding citrus with the meal.
And everyone, please do not ignore the overwhelming evidence that has built about the great importance of vitamin D, the best source being the sun. Sunlight will do good for you. In the winter months, take supplemental vitamin D of at least 2000 IU daily. I was just outside on this gorgeous day and the difference the sunshine makes is incredible.