Cancelled key-fit - loss of gym membership

I joined Key fit in September 2015, and joined Virgin Active. I moved to a better medical aid plan, and lost my key-fit benefit, without Discovery notifying me of such a change. My gym membership now went from R198 to R650, and I paid an upfront fee in September which will now most probably be lost. What should I do to rectify this with Virgin Active, and join Discovery Vitality, as they are clearly at fault for not notifying me that there will be a change. I will most probably have to pay another lump sum to join via Vitality, which is not acceptable as I am paying double then. <div><br></div><div><em>(Supplier name changed from Discovery Health to Discovery Vitality &amp