Hi there @Monica_FG welcome to 3Community.
I'd be happy to look into this for you. To get started I'll need a little info from you the first thing I need to know is, in your online banking is the top up showing as complete or pending? If it is pending there is no need to worry, it'll drop back into your account in 5-7 working days depending on your bank, if its shows as complete please pop me a PM with your name, number, address and date of birth. Also please share the number you topped up in error.