Lenovo — After three months issue not resolved.harassing customer

I raised a complaint on 22 may 2020 as my laptop was not working. After one months their engineer visited me and he told there is problem in mother board so he sent a request to lenovo service centre to provide mother board for my laptop. After several followup i get to know that they have ordered the part as they dont had the mother board in their stock so it will take three weeks to come. After 3 months also they dont have the mother board and when i called customer care they said its still in transit. I wrote the complaint in twitter, after several attempts they said that as parts are not available they will provide me system replacement and they have received the approval also, their executive will come and will seal the laptop. Today on 10th aug executive visited and again he said that they will provide me the damage part replacement and he denied for system replacement and left. Its been three months now and due to pandamic we all are working from home and classes of kids are also going online so just imagine how much my work has been hampered and also my daughter has faced so much issue as laptop is not working. They dont have value of their own words. Is there any timeline for the resolution of complaint or not?? And if they have crossed the deadline which they asked was 3 weeks and its been 3 months so how much patience i need to keep?? Now if they wont resolve my issue within 48 hrs than i will drag this issue to court. My complaint no is [protected]. Plz do needful. I would also request others plz dont buy any products from lenovo as their customer service is pathetic...