Virgin Active wont refund me for their incorrect billing

Very disappointed in Virgin Active La Lucia Virgin active debited me (TWICE) at the full price, when I am a vitality member, and should be paying Discovery rates. No one will get back to me, and everyone keeps pushing it onto the next person. How do you justify taking over R2400 from someone in error, and then simply refuse to give it back. Be fair Virgin - youre losing 3 family members by this ******* move - whereas you could fix it, and keep us all paying monthly for the next 2 years. Your call - but Ill be taking this further if not refunded.