Cancelled gym discount

I was charged a full gym membership fee by Virgin Active, after a phone call I found out that that Discovery Vitality had sent a message saying that I am not a vitality member (December 2015).<br> <br> Seeing that I have been and still am a vitality member for approximately 5 years. I find this unacceptable, I was not notified that my discount would be revoked, which should not have been revoked.<br> <br> I was charged the incorrect amount this month due to Discovery Vitality mistake or \ glitch\" . I would like Discovery Vitality to rectify this as soon as possible and refund the extra membership fee they instructed Virgin active to take off my account. <br> <br> <br> <br> "