Error with displaying total amount on prepaid card

When I go to top up my card in the app, instead of displaying the total amount that will be on my card, it says the total amount is equal to the amount that I am topping up by.
(E.g. if I have £16 and want to top up by £40, instead of displaying £56 as the total money I have on my account, it will say £40)

It might be useful to let us know where it says this. In the app itsel? In the top up notification? As much detail as you can provide would be useful.