Mophie 3-in-1 travel charger with MagSafe isn't charging iPhone or Apple Watch

I bought this charger January 2023 ($189.99 in Canada, an exclusive item only sold through Apple), and last week it started malfunctioning... my watch and phone would not charge (in fact the station drained my batteries further). I called the Apple helpline, and after 10-15 minutes talking to a representative, was told to go to my local Apple store. I went to my Apple store, and at first they told me, "Although you bought this at this Apple store, this isn't an Apple product, so we don't warranty these products. You have to contact Mophie (Zagg)". I replied that I was very upset as I'd been told to come to the store. At first they tried to "help" by registering my product to initiate an warranty request with Zagg, but it seemed to be impossible without a serial number (only available on the box, which was thrown away last January). The store supervisor decided to take pity on me, and finally agreed to exchange my charger for a new one since I couldn't even register the product to request warranty service.

I was a little disturbed about this whole experience, but relieved to have a new charger. However, the charger worked for TWO DAYS and then it also started malfunctioning, in the same way as my first one. This afternoon I searched this product online, and found many people who have had the exact same problem as me with this exclusive Apple Mophie product. I'm reluctant to go back to my local Apple store, as they made it abundantly clear to me that they think these kinds of products are not their problem. However, I cannot help but wonder, WHY is Apple selling this expensive and exclusive Mophie product, made especially for Apple products, only sold at Apple stores, and refusing to take care of their customers who encounter a problem with this product?