If you have a 99 percentile or higher, you have a good chance of getting a call from IIM Calcutta. Many students with less than 60% are enrolled in IIM C.
IIM Bangalore is unlikely because they place a high value on the profile.
The only thing you can do right now is to perform effectively on the CAT and improve your profile. Attempt to improve your CAT score. Do a variety of certifications to raise your profile. Never waste your valuable time worrying about your academic performance. What has been done is done, you cannot change it.
Some of my friends studied in both IIM Calcutta and Bangalore. According to their experience, it is pretty clear that it depends on your CAT percentile. Your chances of getting a call from IIM Calcutta or Bangalore can be determined by the following factors:
Overall, 99 percentile is good enough to get you into FMS and IIM Calcutta. However, if IIM Bangalore is your primary goal, you must score at least 100 percentile.