Hi! Thanks for bring us the question!
In my opinion, taking action against the showroom dealer would not be a wise course of action and would add to the agony you have already been through, on the financial, physical and mental front. It would have been a mindful action if you had suffered some loss and need the dealer to compensate.
I would advise you to just take the RC book back from the dealer and visit the RTO yourself and get going with the name correction and selling the bike.
For name correction, you have to submit -
> ID Proof with the name you want in
> Original RC Smart Card with Copy of Road Tax Receipt
> Invoice and Insurance with matching name as per ID Proof
> Request letter to report mistake and change in name as per given document.
Hope this helps. Good Luck!