OnePlus - My phone screen damaged due to there software update no solution after more than 40 days

I was a user of One plus phone model ** Pro. Which i bought at ***** Rs. Suddenly a green line appeared on there screen which was due to their software update . When I approched them on **th july at their kandiwali service centre, they accepted that it was their fault and they will change the screen free of cost. But they said it will take upto ** days as they don't have parts available with them. ** days was huge for me I asked for any other alternative. They said no that is the only solution we can provide. They said u have a higher model for lower model we are giving an option of voucher upto **k. But that is not applicable for your model. I said then i have to wait i don't have any other choice. But its almost more than ** days and I didn't get any solution for that. I am from a service provider industry and I have to carry a mobile with all the functionality of emails and many apps. So i was forced to buy a new phone immediately and I had a deal with the dealer that if i will give my old one plus ** pro phone before **th july **** he will return me ** K. Now today its **th July and still no solution from the oneplus side. My that deal is also scrapped. I am fedup with the oneplus service. I am following with them like anything and they ate mentally harassing me by giving a new date everytime. Now i really fedup. I don't know what to do