Byju's — 11&12 SD card

My son completed his CBSE 10 Board exams 3 weeks before. He was studying Byju's for last 5years.His course is K 6-12.He doesn't have 11&12 CBSE syllabus SD card. I was trying to contact mentor for last two weeks. The number [protected] which I called, I heard only the voice message the number doesn't exist. I mailed again and again, but I didn't get proper response. Please concern this and solve my problem. How do I contact the mentor or any other executives. Orelse please send me the SD card.
Name : MARSHALIN CYRIL S
NO : [protected]
Course : K6-12 Tablet learning