[Resolved]  Bajaj Allianz — ncb letter request while selling the car

I sold my old car as a trade to dealer on 06-mar-17 which was running under 45% no claim bonus (Ncb) for comprehensive insurance number hba/00404011 running till 03-aug-2017. I bought a new car on 7-mar-17 and took a fresh insurance with hdfc ergo and when i asked to transfer my old ncb to new car, bajaj allianz said that i had to have a copy of rc transfer with new owner name to initiate the process of ncb transfer. So i waited till the dealer sold the car and got the new rc for the person. The dealer sold the car around early august and the new buyer took a fresh insurance by himself. I got a copy of the new owners rc copy but they declined to accept it since that rc card did not have the date of transfer. Then they harrassed me to go get the the b-extract from the rto office and i got that which showed an effective date of 10-aug-2017. So effectively rc transfer date was after the expiry of my old insurance. Now that old policy is expired and there was no claim on the old policy and car is also sold, they finally agreed to give the ncb letter. They issued the ncb letter stating that my earlier policy was issued with ncb of 45% from 03-aug-16 and there was no claim reported till 28-oct-17. The last line says that "this ncb can be availed within three years from 28th oct 2017.

Now when i gave the ncb letter to hdfc ergo, they are saying that they cannot include it in my current ongoing insurance for my new car since this letter is from 28th oct 2017.

Who is at mistake here and how should i handle it?