Sony India — problem reoccurs even the part is replaced by their service centre

I purchased sony xperia xa1 dual sim on oct/nov 2017. From may 2018 the touch screen was not responding properly. Due to busy schedule i went to their service centre (Thane, maharastra) roughly on aug/sept/oct 2018. Due to warrenty period they have freely replaced the touch screen part and returned the mobile set with in a week. Again the problem started. I came to know that the model itself has fault. Today (14th dec 2018) i visited their service centre at thane. They asked me to resubmit the phone. After checking it they will decide to charge or not according to the problem. I am not ready to submit back the phone again. I wanted a replacement mobile from sony or free replacement with a guarantee that if it occurs again they will replace the mobile set.