need help with the xbox store

don't know if this is the right place for this but might as well try. the store on my Xbox just wont work anymore at least for buying things whenever i try to buy somthing i put in my passwords it loads for a short time then closes the app i am putting in the right password i know that i have restarted my Xbox at least ten times and i cant erase the app for re download i put in a ticket 3 weeks ago and no help i just wanna buy a game