Ridiculous return policy

I am a new client to Samsung and recently took out a contract for a Samsung Galaxy S6 Edge. The phone is great and I love it, when I first got the phone it was extremely fast to charge and I noticed this week that the phone takes forever to charge, I then figured out that it was the USB cable that is faulty, I then took it to MTN where I took the contract out and guess what they said, since its within the 6 month warranty period I must bring the box back with the charger and phone and they will replace everything, this is so ridiculous as the USB cable is the only thing that is faulty and I do not need a new phone, apparently this is the policy.