Mahindra And Mahindra — about my new scorpio registration issued by dealer silver jubilee motors

Res sir,
I purchased new scorpio m2di on 31/12/2016 from silver jubilee motors,
I got the invoice and delivery note on the same day.
At that time i informed dealer's concert sale person that i want to take the choice number for my vehicle.
So that i got the choice number receipt from pimpri chinchwad rto on the date 02/10/2017, i submitted the copy of that choice number receipt to the showroom on same day.
After 10 to 15 days showroom issued me the number plates and confirmation of that choice number.
Then in april when my service date was came, i took my vehicle to the silver jubilee (Mahindra authorized dealer) for 1st service.
At that time i also meet the sales person and i asked him about choice number, so he told me not to worry, your number is conformed to the rto registration from our showroom.
Then on 08/07/2017 i got the call from silver jubilee motors, regarding when will you take the choice number for scorpio..
I was shocked to heard that, i told them that i had took the choice number and submitted to your showroom on 10/02/2017.
Then they told me that my choice number receipt is expired.
Then next on 10/07/2017 i went to the showroom for inquiry about the choice number issue...
No one cooperate with me and also not going to take any responsibility about my vehicle which was taken by them..
Then worst thing is that, showroom legal adviser of silver jubilee motors send me the legal notice about not to register your vehicle and number..
After 2 hours sitting in the showroom, they give me rto tax receipt which paid date is 07/jul/2017 means last 3 days back they paid my tax...
How irresponsible and careless service provided by silver jubilee motors.
I am frustrated through mahindra dealer.
Is it my mistake to purchased mahindra vehicle?
So i kindly request to the mahindra & mahindra to take serious action against dealer silver jubilee.