Peninsula Battery in South San Francisco review: Car battery

I purchased a car battery from Peninsula Battery in South San Francisco in October of 2022. Today, March 22nd my battery died. I then took it to my local mechanic thinking it could be the alternator because it could not be the battery, I just purchased a BRAND-NEW battery back in October because usually car batteries last more than 5 months especially a brand new one. However, my mechanic stated that it was not the alternator but the battery. My mechanic also stated that the battery I purchased from Peninsula Battery he never even heard of the brand of the battery, and he has been a mechanic for over 30 years. My mechanic stated that this off brand battery (that I paid over $200 for) was not holding a charge. I advised him that's impossible I just bought that battery back in October. Anyway, He then hooked up the battery I bought at Peninsula Battery to his machine and he showed me that the battery was not charging. I immediately said "ohh no" I got scammed! I now have a brand-new battery that cost me $300.00 and when I reached out to Peninsula Battery and told them that I would like a refund for my the defective battery they sold me the manager said "no" because I did not have my receipt. The owner "Sean" stated that since I did not have a receipt, I was not entitled to any compensation. So, I'm on this board to complain of the unfairness Peninsula Battery Inc in South San Francisco and letting the consumers know of the unfair practices of this business. I would like for the county of San Mateo to investigate their practices as they have scammed consumers in the past based on their Yelp reviews. Thank you