Vivo 1906 Phone Problems After 21000 PKR Refund Request

I am writing to complain about my Vivo 1906 phone and to request a full refund of the total amount I have. This phone was sold to me in Karachi by a relative who brought it from another village, together with only the mobile and the charger. I paid for it in parts: first 8,000 PKR, then 6,000 PKR after two months, and finally 7,000 PKR in the last month. After paying all this money, the phone has given me many problems and I am not satisfied with its condition or performance. Because of these problems, I contacted Vivo service for help. Despite reaching out, I did not receive a clear or satisfactory solution for the issues I am facing with this device. After spending a total of 21,000 PKR, I feel that this phone has not provided the basic reliability I expected. I request that Vivo review my situation and arrange a full refund of the amount I have paid for this Vivo 1906, or provide another fair solution that fully compensates the money I have spent.