It is understandable that your 12th and graduation scores are not up to the mark for the Indian Institutes of Management (IIMs) A, B, and I. Even IIM L may also be difficult for you to secure a call from because of your low scores. However, it is important for you to know that there are other options available to you. Even though it may be challenging, it is still possible to secure a call from IIM C and IIM K with a very high CAT score of 99.9 or above. Unfortunately, it seems that IIM Shillong may also not be an option for you due to your low score in 12th.
Given this situation, it is advisable for you to give your best effort in preparing for the Common Admission Test (CAT) and also consider appearing for other entrance exams like the Indian Institute of Foreign Trade (IIFT) and the Xavier Aptitude Test (XAT). With a decent CAT score of 99.8 or above, you may have a chance at prestigious institutes like the Faculty of Management Studies (FMS), the Management Development Institute (MDI), and some Indian Institutes of Technology (IITs).
Additionally, keep in mind that the weightage of the entrance exam and interview is very high for IIFT, so it is important for you to prepare well for that as well.
It is worth mentioning that, although your current scores may seem like a setback, it does not mean that your aspirations should be limited. Keep in mind that there are many other options available, and with hard work and determination, you can still achieve your goals. Remember to keep your head held high and keep pushing forward.
One of my friends had a past academic record of 69/70/58 which you can infer is much worse than yours. So I think I can present to you a clearer picture regarding your scenario.
In CAT 2017 he had scored 99.59 percentile and got calls from all new IIMs (all IIMs established after 2010) except IIM Rohtak and converted IIM Udaipur, IIM Sambalpur, IIM Bodh Gaya, and IIM Kashipur.
You should get work experience of at least 2 years before applying for IIMs once again. It will certainly lower your percentile requirements.