repair waiting period

hi got this wifi router from Telkom Maponya mall Soweto and its still under the warranty but the charger is no longer working (faulty) then the agent at the shop says the wifi router need to be booked in for 28 days and the question is what do I substitute with in the 28 days that they will still charge me for ? do I just pay for something that I have not used? what is customer service? I was sent to 3 different people none was willing to help? why do we get this treatment when we only need help we have to beg for something we paying for? this is under warranty what was difficult for the agent to change ? the only part I don't understand is the 28day repair wait. that long while paying its so wrong.for only a charger? worse part she took the new charger from the store room checked it with the router and it worked . then still says we have to book this one in for repairs.