Amex Prepaid Card Complaint

Amex Prepaid card department,

General purpose card Unauthorized transactions/trans. issues Illinois

I tried 3 times with a lot of time to let them know I was disputing a groupon charge for - I told them i only had my receipt showing it was paid they closed it 3 times saying i did not send information when just a few days ago they said they got it. They can not understand language barrier. I should be treated like a customer and groupon has no way to get a hold of ceo and write which i did no response