App store

whenever I try to download anything on App Store it always makes me sign in and then asks me for my card informatio. When I put that information in it says that there was a billing probl but Im not buying anythin. Everything I try to download is totally free. I don’t know if I owe money or not but I’m pretty positive that I don’t. I tried going to the tmobil store to ask for help but they just said to update my phone and maybe it would work but it didnt. None of my apps are updated so there shutting me out until I update it but App Store won’t let me. I NEED HELP!!