Air India — shillong flight cancelled

Address:

Mumbai City, Maharashtra, 560075

Kavitha rao a single lady travelling with a 10 year old child from shillong to kolkata on 02 june 2018 on the air india flight no ai9712.
Since my final destination was bangalore, i had a reconnecting flight from kolkata to bangalore in indigo 6e-342 at 8.20pm
The airport authorities informed us at 3.30pm that the flight from shillong is cancelled due to some technical fault and all o[censored]s will be sent to guwahati.
As my flight to bangalore was from kolkata, i asked them what can be done in this situation, they said they cant help me as my ticket from kolkata to bangalore is on a different airline. But then since i was a single lady with a kid, the other passengers also insisted that i be helped.
One mr vishnu and another gentleman assured me that they will put me on guwahati-bangalore flight which is to depart at 6.56pm from guwahati on 2 june 2018. They informed me that the flight no is ai775 and i will reach bangalore. I confirmed the same with him twice…
On the way i cancelled my indigo ticket as they had assured me that i will be sent to bangalore from guwahati.
We had very less time to reach guwahati airport, but somehow we did manage.
On arrival at the airport in guwahati, i ran to the air india desk. The person (Mark i think a foreign looking person) started throwing a tantrum that i cant take the flight as my connecting flight is with indigo, but i told him that mr vishu assured me that i would be sent to bangalore.
He spoke to mr vishnu on the cell, finally issued me the boarding pass. He did not tell me anything. By chance i managed to ask him as to why the ticket says ccu instead of blr, he conviently said.. Yeah you are going till kokata. I informed him that mr vishnu assured me that i will be sent to bangalore.
He told me that since my ticket was till kolkata, they can send me only till kolkata. I informed him that i cancelled my indigo tickets based on their assurance.
He said he could not do anything and finally i had to go to kolkata. I had to stay put with some acquaintance airport and book fresh tickets for the next day with jet airways at double the cost.
How can a national carrier be so rude and unsympathetic towards its passengers. For no fault of mine i had to endure the hardships and pay an additional amount.
Why was wrong information provide to me by mr vishnu?
Why did the person at guwahati airport not tell me that the boarding pass is only till kolkata?
I do understand there may be technical issues, but that does not mean that you just provide some wrong information to the customers.
Request you to please compensate me with rs 10, 000 the extra amount that i paid for the new tickets with jet airways