asked to serve notice period on offer letter

Dear Seniors , I was given an offer letter by a company but the location was not suitable to me . After discussion over phone they agreed to give the location that I wanted . Thus I joined them . After 4 days they asked me that I will have to travel to different locations and I did not like the culture of the company and neither my role , so I just sent a two line email stating that I will not be continuing with them. They did not issue me any appointment letter and I was working on an offer letter . Even the company ID card was not issued to me . Now the head of talent acquisition send me a SMS that I need to serve the notice period for 1 month. I told him that I don't have any document stating that . He said he wanted to give me the appointment letter but since I did not work he was not able to give it to me . He told me that since the company bought a desktop for me , I have to pay the one month notice period . Please help me in this as I don't want to be harassed by this company