Malfunctioning laptop and poor service

We bought a laptop for my younger sister sometime lastyear and we had spent around 11000 for everything in total. The laptop started giving us problems barely after 4 months of purchase. It started switching off on its own, rebooting and it was difficult to get anything done. We reported and took it in for repairs. It has been going in for repairs eversince and coming back with the same problem. We then took it in again February this years n they stayed with it until it was out of warrantee. After that they tell us that they need to replace the RAM which is around 3000 and we need to pay since it is out of warranty. Mind u it has since been with them until it got out of warranty. I reported to their Facebook page which was totally useless as they not assisting. Can someone really actually help!!!