It's Series 4, not Series 6. Series 6 was All Stars, which is why you might be getting confused.
It's the one with Latoya Jackson, Nene Leakes and Star Jones <3 it's BY FAR the best celeb season, I suggest you give it a go if you are short on stuff to watch. I'm deffo rewatching it as it airs on BBC
It's on every Sunday night.