Fnb verification app not working on phones

Fnb changed there payment verification from opt to have to approve on FNB app. This system is not working on my phone because the minute I minimise the website page I am trying to make a payment on eg takealot , to go and approve it on the FNB app the website page reverts back to payment page . So we're I was able to pay for things on my phone I must know shop and make payments via a computer....not all South Africans have laptops or computers. This is very shortsighted of FNB.