Billing

I received a contract phone from Cellc mid April and now it's damaged and does not detect the Sim, I took it in for repairs and now they want me to pay for it, which is the part that i don't understand the phone is supposed to have one year guarantee from the service provider and also one year from the handset manufacture, i just cant understand as to why i have to pay R1800 for the repair where as they supposed to be fixing it for me, just want to cancel my contract and want nothing to do with cellc i seriously thought it was the best but they proved me wrong...