I sent Experian a dispute letter via CERTIFIED mail with return receipt by USPS. It was delivered last week and I got my receipt that experian signed for it. Upon calling them they claim they were not received and that it takes maybe 1-3 days to upload my mail to the system. Well it's been 5 days since they were delivered and they are saying the same thing when I call them. Not sure how to proceed. Never had this issue with TransUnion or Equifax .