Unhappy about service

I bought my Hyundai brand new from your branch in brackenfell the beginning of last year. So far I've been happy with the service when I take my car in to be serviced but now my battery is giving a problem it has for a while now but every so often it won't start so that's why I have not brought it in sooner because it then works fine for a few months and all of a sudden it doesn't wanna start again. So I phoned brackenfell and I asked them is it covered they said there's a two year warranty on the battery the car isn't even two years old so I said okay fine I'll book it in car went in yesterday waited the whole day only to find out that it's two years or 40000 km. Why didn't she mention that.... My car has done 40400km. So now because of 400km you guys don't want to cover it. I'm very upset and sorry I chose Hyundai and have changed my mind to trade in for another Hyundai because of your service. I have been with other car brands and have never had this experience before. I feel it's unfair to not help me because of 400 km I have logged a complaint at brackenfell they have not phoned me back yet. I thought I'd just let you know that you got one very unhappy customer and I feel I don't want to do any more business with you guys. Thank you very much Mrs Bartlett