"As others have said, that wasn't their fault as the actress left so suddenly, but..."
Did she leave suddenly? I thought she gave an interview where she said she had only planned on being in it for three years. It does seem strange that she would leave since she was a well liked character. She was the one we love to hate in a cast full of goody-two-shoes.
I've also heard it said that British actor contracts are different than Americans. They are only signed for a year and sometimes it's not clear whether the show will be renewed and so they take other work before the decision to return is made. Could that have been the case?
If anyone ever tells you that you put too much Parmesan cheese on your pasta, stop talking to them. You don't need that kind of negativity in your life.