iBall — Abruptly switching off of 'I ball Bizniz Mini Tablet'

Address:

Express Road, Kanpur Nagar UP

I have purchased 'I ball Bizniz Mini Tablet' on 26.05.2020. It was in good condition. Now, from the month of December 2020, it shows that the charging of the battery of the tablet was stopped on 17% or less. I contacted the service center at Kanpur in the third week of December 2020. They returned the tablet after 20 days saying that now it is ok.
The problem of charging was resolved.However, since then a new problem arises and my tablet is abruptly switched off during work even after showing 100% charging of battery. On approaching the Service Centre they guided me to change the battery from anywhere in local market to solve the issue which is beyond appreciable.
Please guide me or issue suitable instruction to the Service centre so as to cope up the issue please.
Regards,
S.K.Kanchan