poor service from SD GATES NORTH COAST KZN

Sherwin sold me a second hand gate motor guaranteed its 100 percent working unit. the electric fence technician i use for my repairs Brain knows Sherwin and Brain collected the unit to install same. after installing the unit my gate only opened and closed for 3 days. brain came out and found the battery on the gate motor was flat. the electronic board was removed by Brain and sent to a specialist company to check same. cost to repair is r650 on discussing same with Sherwin the supplier he refused to pay for the repair. i then suggested we go 50/50 on the repair but Sherwin whos the owner of SD GATES refused. to me this is poor after sales service and detrimental to his business in our area of the North Coast in KZN FROM Umhlanga in the South to Richards bay in the North