toyota estima 2006 hybrid battery or alternator

[AliA]

I got my toyota estima 2006 hybrid Battery replaced by a Japanese import specilsit in Romford(Bari Autos) due to hybrid sign on dashboard.Since its replacement,the sign is still appearing after few days.He offered 6 month unlimited mileage warranty and I have had 3 visiits post installation due to sign appearing again.Last week he kept the car for neraly two weeks and gave me back again with usual words of staisifaction that it would be okay now.He also started saying that other parts such as alternator might also need replacement.Can someone suggest if what signs should somone notice to ensure it is hybrid Battery issue or alternator?The dashboard has continued to show hybrid Battery fault issue afte few days.I am stuck with this cowboys.Please suggest what should I do.