Asus India — about my asus zenfone max pro m2

Hi,
I am using asus zenfone max pro m2 from almost last 6-7 months. I have already update my 3-4 times as per system updation given by company. First 2-3 update was good but after last update i am facing some problem with my handset. Noticing that battery backup reduced to almost 10% from before. That is not the major issue. The most important matter is calling sound mean hearing speaker sound is reduced to atleast 50%. This horrible to me. I can't speak properly in public place not even within 4-5 people around me. Every time i need to go to a silent zone. This is simply breaking my faith on asus. Suggest any solution.