In utter shock of Samsung customer service

My Samsung watch has been faulty for a while, the heart rate monitor is consistently low during high impact cardio workouts. I know this because I have been tracking my workouts for years and I'm on the vitality program for points. Further, I compare it with my huawei watch which works perfectly, my Huawei watch has been a life saver during this time. I took my watch in for repairs as it is still under warranty, I later received an email from Samsung stating that no fault was found and I should collect my watch. I reached out to Samsung again, explaining that there is definitely something wrong with the watch and I need them to help me. They maintained their stance. What I would like to know from Samsung is what am I supposed to do with a watch that does not work? My watch is still under warranty yet the makers of the watch cannot help me.

I'm taking this matter to the ombudsman.