Discovery Health

I joined Discovery Health on the 1 May 2018 they never deduct money from my account I did not even know I was a member on the 1 June 2018 the dicide with out telling me to deduct double payments.When I phoned them they told me they forgot to deduct the 1 May 2018 so the took double payments on the 1 June 2018.Please assist in this matter they told me they made the mistake but its not there problem