Bad quality devices

I have a 24 month mobile phone contract with telkom mobile. My device has a built in battery and it has been giving me problems for the past few months where it would basically be fully charged but the device would go off for no reason and when i plug the charger back into the device it would show that the device is on 3% battery life... I then called telkoms customer care who then advised me that they cannot help me because i had disposed of the original packaging that the device had initially came in. Lately my device started switching off at 100% - if i had wanted a landline i would have gotten one. I called the call centet again and they had referred me to the branch. When i got to the branch they referred me to a technical branch... At the technical branch they had told me that they cannot help me because the contract was 18 months old. At this point i was irritated because i was being sent from pillar to post and the arrogant looks that i had gotten from the staff. My main irritation is that why would a service provider provide their consumers with device contracts that last for 24 months however the device itself doesn't even last that long???!!! And when you ask for assistance they make it seem like you have done something wrong... Poor quality service and products...