My Redmi 4 32GB was perfect in all aspects. After about 2 months of usage suddenly i am facing slow charging problem. After overnight charging my battery is only 10%. Estimate shows 7 to 8 hours to charge fully. Even if it shows 2.45 as usual, it does not charge fully. Now I am using along with charger. Last one week I am loosing many calls due to phone switch off. Please suggest remedy. MIUI