Telkom Complaint

I would like to report the bad experience I had with Telkom. last year I bought laptop on 3 year contract that I am still paying . I bought it in April 2017 and then March 2018 it was crashed couldn't use. I was busy with exams so I couldn't go there on time .. when I went there with a laptop they said I must go to visit the assessment centre and I went there but I went after the warranty so they said I must pay R7000 for the work done. my question is that why did they sell product that couldn't even last for a year? why must I pay their contract for something that is not working, I even asked them to check IP address to see when last did I use the laptop.... please assist me what to do I am paying almost R500 monthly for a toy that is not working