Currensea takes funds by direct debit after your transaction has taken place. Some banks assume that direct debits recur monthly, and so they can incorrectly predict upcoming payments based on the latest Currensea payment.
As an example, if you did a £50 transaction on 5th June with Currensea, your bank may incorrectly predict you will have another £50 transaction on 5th July.
You should ignore this - the money will not come out as it is an error with your bank. Please do not cancel your direct debit as this will impact future usage of Currensea.