Cash Crusaders

I bought a phone(second hand) at cash crusaders with 6-months warranty for R4 500 which was no issue used for 4-months and the phone stopped charging took it back to the shop and the guy there took the phone and gave me a a slip they are going to look at the phone two weeks later I call as I was given no time frame as to how long I must wait lady told me the phone is back but they techs don't have the necessary part I go into store and I'm told I must pay for the repair no detail as to why I'm paying where my question is then is the phone not under warranty?