Defective exterior paint

I bought my paint at build it and I told them I want it for outside and the salesman convinced me to take the build it plascon paint however I’ve discovered that when it’s raining the paint melts and coming off but the guarantee is 8 year I bought it on the 27 of December 2025 to this date the paint has been washed off by the rain my outside wall looks soo terrible I am very dissapointed as I thought Plascon paints are of quality i have sent numerous emails to both build it and plascon but nothing have been done to this date and I will not let this slide I have spent lot of money buying this paint.