My bank recently replaced my Mastercard credit card with a Visa one, despite being Mastercard for years. I also have a Visa debit card. You don't have control over this :(
You can just fill out a form online and get another credit card from someone else.
Here in Sweden many former Visa outfits have gone to Mastercard, so now it's sort of hard to find a Visa CC here. I've gone out of my way to have one Visa and one MC though.