Yes @Dancia69 when topping up online there can sometimes be a slight delay with authorising the transaction and adding the credit to the account, when happens do not try or click to complete the transaction again. If you check your online account or phone Application, any top ups or bundles will always show there.
When you check your bank account, you will see the payments will be ringfenced as pending authorised transactions, if the duplicate payment is not claimed by Vodafone this should return to your available balance certainly within the next 4 to 5 working days. Banks are usually unable to cancel authorised pending transactions but no harm contacting the bank for help and advise.
If you need help from Vodafone, for account access speak to Vodafone through Customer Service channels, there is also the Social Team here: Contact Us
