Its an automated message that says your Amazon Prime acct is being auto-renewed for $399. If you want to change your details or subscription then press 1 and so I did - you get put thru to a call centre with dodgy people.
I suggest blocking this number immediately - they are scammers.
and clearly foreign , which is why the message is automated, it not even a real person - another mobile number also leaves the same message - block this number too 0426 603 652