Debited twice in 14 days.

I signed up with Virgin Active to be debited every beginning of the month and this arrangement has been the case since 2018. This month I was debited on beginning of the month the 1st July as per usual. Now to my shock I get notification that that Virgin Active have tried to debit me again on the 14th July to which it failed to insufficient funds however that's not the point. The point is how come I'm getting debited twice in a month!!!!!! What the hell is going on.