Not able to use credit card

I have received a new credit card, but cannot activate it becasue every time I open the Banking App a message box appears saying: No internet connection found. RETRY. This is despite me trying it in three fully operational wifi settings, rebooting my phone countless times and trying again and again. Then I go onto the bank site, to see if I can activate the credit card on the website, but I cannot get in because of the authenticfication process which requires you to open you Discovery Bank App. And I can't open that App because I repeatedly get the same message -'No internet connection' RETRY! So I am caught in a loop.