Oncology department in Aster -opinion

My mother was diagnosed with colon cancer after undergoing a colonoscopy at Amrita. We consulted Dr. Nikhil (Oncology) at Amrita, and he seems to be good. However, since the patient services at Amrita are a nightmare, we are considering shifting her treatment to Aster under Dr. Arun Warrier and Dr. Durgapoorna. Does anyone have experience with oncology at Aster or with Dr. Arun and Dr. Durga? We have insurance.