Bad service

I bought a contract cellphone LG G2 in may 2014 which I am paying R437,00 every month.in march 2015 it started freezing,i then took it to savannah mall polokwane,they then send it to midrand for evaluation,i am still paying the cellphone and they're expecting me to pay R2,438,90 for them to fix it. they decided to sent back my cellphone to me withought fixing it. I got the message today on 27 august at 07:00 am saying that my device is ready for collection. how on earth? please assist me on these matter.