OTP NIGHTMARE - UNABLE TO SPEND MY MONEY DUE TO AUTHENTICATION DEPARTMENT HAVING PROBLEMS !!!!!

Been wasting half a day out of my work day trying to sort out why i am not receiving OTP's in time. Tried to use card this morning. OTP's coming in so slowly that I kept putting in an old one and eventually got blocked. Then phoned in and got the card unblocked after speaking to the authentication department. They said ok they have sorted it out and it was all fine. Now I am trying to make another purchase and I AM NOT RECEIVING ANY OTP. What is going on with yout OTP system ?????? THIS IS UNACCEPTABLE I CANNOT USE MY DISCOVERY CARD !!!!!!