Standard Bank 'hot card'

Recently I've been trying to use my standard bank app to buy but I couldn't because it said 'hot card' which I don't know what is the meaning of that, I went to Kwa-Mhlanga Mpumalanga branch to seek resolution of my matter with the app but they couldn't help me because they said they don't know what caused it, I then took my last airtime to call them the lady I was speaking with said they are going to get back at me but they haven't done that as I'm still waiting for them to get back at me. Mind you I'm hungry as I can't buy food or petrol since my card is not working, my holidays are ruined by standard bank. Please intervene on this matter because I can't even buy food or clothes for my family as Christmas is near. Thank you