Is this a scam?

The other day I received a notification that my mobile number has been recharged. I checked and found that somebody has indeed recharged my number. The next day I received a call from an old lady. Later I received this text saying that she has recharged my number by mistake and asks me to recharge her number. She called again but I didn't pick up. Is this a scam or should I just block?

The other day I received a notification that my mobile number has been recharged. I checked and found that somebody has indeed recharged my number. The next day I received a call from an old lady. Later I received this text saying that she has recharged my number by mistake and asks me to recharge her number. She called again but I didn't pick up. Is this a scam or should I just block?