CNA will not refund Lenovo not working

Purchased Lenovo from CNA Northgate on Edgars account. After a short period it gave only black screen. Kagiso, salesperson at CNA not available. Manager. Mannis gave Lenovo no. Lenovo replaced operating system. Still only get black screen. Mannis, CNA, will not refund/credit Edgars account. said they did not tell me to take it to Lenovo I should have brought it to them. This was never communicated. Was originally told had onsite guarantee. Laptop left at CNA northgate. I want a credit on my account<br> Mannis would not take back for refund would only take in if I agreed to send in for repair....