Congrats on securing a great percentile Purnesh. I think since you have already gotten your offer letter from Symbiosis Institute Of Technology upgrading to CS shouldn't be a tough call. Do participate in the counselling sessions as the number of candidates applying changes each year. So you might stand a chance [ I assume up gradation is the case here ] 

Dear aspirant with this rank you won't be able to get any nit. So since you have got a letter from symbiosis institute of technology go for it. I will suggest you to take vit for cse rather than symbiosis. Because cse is better there than any other private colleges.