Trash devices and customer service

i recently bought a second hand Mercer laptop at Cash crusaders Arcadia. the same day got home and realized that it had no drivers for connecting to the internet - I then took it back the next day and this was fixed - A few days later realized after attending my first meeting with the laptop that the microphone doesn't work - I took it back and that they couldn't fix. After 2 days of going up and down trying to get this sorted with them during my working hours, they then decided yesterday to replace the laptop with a different one. i took the new one home and through out the night it was just slow and i could barely get anything done with it - I woke up and logged into netflix to watch a movie and a few seconds later the screen turned blue with an error message: something has gone wrong please keep your device on while we fix it.. I just let it be and eventually it restarted but after the restart when i logged in the screen will just go blank so i took it back this morning. they have been trying to fix it ever since, i must SAY i have been listened to through out the process however i have been treated like I'm desperate to own this laptop. nothing gets done on time i currently have 3 warnings from work for disappearing because i wanted to get this fixed and every time i go there ill wait for hours to get assistance i cannot afford to lose my job and i cannot afford to go there and wait even a second more than i already have, just so i can get the problem fixed. please i want my money back. you can keep your trash laptops i just want to never enter that store again and the only way is for me to be refunded and ill make sure i never walk in that store again. no one is doing me a favor and I'm tired of being treated as though they are doing me a favor by fixing their trash devices or by helping me when it suits them. i no longer have the capacity to be either patient or nice. i just really never want to set foot there again