PEP Home N1 City

I bought a mobicel phone at Pep Home N1City on Tuesday the 8th September, the lady tried switching it on but it kept loading for a long time, she said it normally does that,I must try it at home if it still does the same I should bring it back the next day, I took the phone home, when I get home it was still doing the same, I put on another sim card on sim 2 slot and tried to open the phone it worked, but when I use sim 1 slot it doesn't want to load,when I took the phone back to PEP, they tell me they will send it for repairs and I must pay, they will charge me, I must pay for a phone that I bought 2 days back, really?