AW10 Braun classic watch - black dial and black leather strap

I am unsure if it keeps the time accurately. It was off by about 15 mins in less than a month. So keeping an eye— in case it was my error. Otherwise the watch is slim and the perfect size. I really like the aesthetic. I contacted Braun, and they told me to get it to a watch store to replace the battery. This is a brand new watch, it shouldn’t have to have this issue