Worst service ever, pep cell higveld mall

My name is Kelebogile Mahlatsi, ***.I bought a mobicel device at pep cell higveld mall in witbank, when I got home I realized that it doesn't respond when I touch it. Seems as though it doesn't have a proper touch sensor. When I returned the device less than 7 days later I am told that it is not a technical issue. Ngobile and the guy without a name tag, stated that as long as it doesn't give them an issue at that specific time when I returned the device, it means it doesn't have a problem at all or it is not a technical issue enough. I am not asking for my money back, I am willing to upgrade it, because it seems as though they have a problem with my return. Please correct this, they said that we are trying to be difficult.