Cognizant — problem regarding to offer letter

Hi team,
I had an interview on 15th december 2018 at manyatha tech park (Banglore). After clearing all rounds i uploaded all documents, my onboarding status is.. (Thanks for accepting offer letter please await an email for doj). Now it's been 3 months... Still status isn't changed.. I haven't received mail regarding to doj.. Please let me know when i will recieve doj mail..
I would be grateful if i get offer letter as soon as possible.
Thanks.