It is a common problem nowadays. After a few years of usage, mobile batteries will fail to give their best. They either get more heated or drain very soon. Excessive usage could be the main reason behind it. Moreover, people do not charge them to 100%, on average, after charging for an hour or a half, they will disconnect and start checking.
Every year, there will be a hundred, thousands of mobiles from various models will be out, so, manufacturers think of stopping the productions of old models as well as spare parts. And, if any user faces issues and wants to replace the battery or other parts, more likely he or she will get disappointed knowing that spares are no more available. Lately, all smartphones are coming with non –removable batteries, replacing it has become a difficult thing.
I think I will go for a new mobile phone since using the defective one while charging is not feasible and one cannot stick to the charger all the time. Carrying a power bank along could be a solution but it is not that comfortable for me.
But, using the phone only inside the home, in a particular room can be done; connecting the phone all the time to a plug point is not an issue. It can be treated like a home number, an alternative for a land phone.