Where's my warranty?

I bought a battery on 29 September 2026. I started experiencing problems with the battery. A few minutes ago I went to Midas Mossel Bay to ask if they can replace the battery,because the water was like boiling inside. I had the alternator checked this morning and a few weeks ago because for some reason the battery wasn't charging. The alternator is 100% fine. So this guy at Midas Mossel Bay told me the alternator is overcharging the battery. I told him,but I had the alternator checked this morning. I asked him if I can get another battery since the one I bought 2months ago is obviously faulty,he told me no I can't have it replaced because of the alternator that's overcharging the battery. I feel this is really unfair because why would the warranty not be valid and I paid R 1476.30. How does this work?