Dexcom Clinical Data Associate interview questions

I applied through an external recruitment agency. Had a video interview with hiring manager. She asked me some brief questions like 'Introduce yourself', previous work experience and SAS procedures. Then started laughing saying that this position is not for you. I can see from your answers and work experience that you are good programmer and should continue that. Kept laughing the entire time for the rest of the interview. I knew the interviewer meant well but laughing like this was distressing for me and I was shocked by this interview experience. Severaly disappointed.

Interviewed thrice 2 telephonic rounds and onsite interview by 6 different people for 3 hours and was given oral confirmation about job offer then followed up by hr over telephone and she also mentioned the joining date then later after 3 months the management says it's a miscommunication and false information and the hr no longer works with them .Total waste of time and unprofessional.