Samsung Mobile Service Center - Stuck in Trap by samsung service center

I have purchased mobile from Amazon on *th March, then after **-** days mobile was having issue and not working lockdown was going as soon as lock down ends I visit samsung service center Katraj Pune, they kept my mobile for almost * month and said we change mother board, for this I have to call them several time and visit service center. They give me mobile back after month it work for around *-* days again same issue appears I again visit Samsung service center call customer care toll free number call area manager they said that they will give me mobile with *-* days again same issue encounter that service center person was so rude including area manager. Again they give me back my mobile after *-* days and said it was working and then I encounter new issue that my mobile is not finding network same sim card was working in another mobile I was very fustrated I again escalated issue with samsung toll free number they said they will provide me replace or refund after again almost ** days they today call me and ask to take coupn of amount where I can buy any samsung product of same price, mean while they have provided me stand by very old model mobile, I didn't use that phone at all I use my spare mobile wich I have now when I submit sand by mobile they take the mobile get inside of room come outside and said you damaged screen and you have to pay first screen cost of stand by mobile other wise will not give you coupon I said it is trap and you are doing purposely as I have make your complaint to main samsung they said what ever you want you do and where you want to lodge complaint you go will not provide coupn untill you pay screen charges. So my purchase hand set Samsung M** is not with me they havie it and also not providing me coupn, I am badly stuck in their trap without mobile without coupn. Please help me out in this situation. Service center is in katraj Pune, First floor manik moti complex.