Switching my appointments without telling me

Att texts me that they are "confirming" my technician appointment with the wrong dates and times from what they originally confirmed. Without reason or explanation. They also keep texting and phoning me that the problem has been fixed which it hasn't. My appointment is for the 5th not the 21st. When I call they say OK the 5th and then send me 3 more texts saying it's the 21st with different times in each text.