First Time Car Buyer

I bought a car last year May with a sales person by the name of Wian, He said they will replace my windscreen and he would book for me. I have been following up and have screenshot of our whatsapp conversation where he said they booked in Montana after months of months of enquiry from july to August . The last time he said he booked but couldn't provide the address, when i now try to follow up this year he told me he is no longer working there and now the company says they cant assist me and the owners will be rude to me should i come to their premises with this query because there is nothing they can do for me as the person who assisted me no longer works for them. Which to my surprise how does that involve me as a customer? PLease help. First time car buyer