macbook air shuts down at 65

Hi. I recently got a macbook air M1 (old model but new machine). It semed fine at first, on the first day right after the purchase I was customizing the wallpaper, downloading needed apps, browsing youtube.. very happy with my new laptop.. then it shut down. It only turned on when I plugged the charger in. It turned off and started charging from 1% battery. I thought weird, supposed it was higer than that before the shut down, but maybe i was mistaken. Ok, I let it slide. I charged it untill full 100%, but some SHORT time later it shut down again. In a span of a few days it shut down so frequently that i finally noticed that it did so when the battery reached down to 65%. Then it shut down, I plug the charger in, and it always started charging from 11% for some reason. It charged bach to 60-70% very quickly, practically jumping 11% then right to 14%, then right to 20% etc. but from 70 to100% it charged very slow.

5 days after i bought it i was so fed up with this - that I managed to film how it happened TWICE in one morning, and returned the laptop to the store and send them the videos, desribed the problem and asked for the refund.

Unfortunately I live in a country where there is no official Apple store.

So, the shop held my laptop for 10 days, then they replied that there is nothing wrong with it. They even added a photo of the battery at 55% (which is very easy to take when you charge the laptop back after a shut down) and photos of the battery health analysis. But when I had it - the battery health analysis also said that the battery is healthy and fine and it didnt show how it shut down and jumped from 65% to 1%.

The want to give me this defected laptop back and they won't refund.

What should i do???