Card is blocked

I have been using my card everytime sometimes cash . All of a sudden they say my card is been blocked because unsual activities i should contact them i direct on the app no reply. Google they number there's no where we can call them . Now i cant use my card a i have 75 promo code i need to use but they not willing to help and i dont know why do you need to have a card loaded to use promo . I started using uber i tell you they service is perfect