Faulty Device

I purchased a Lenovo laptop which has been slow functioning since I bought it. I purchased it on the 2nd December and today is the 8th December 2020. I took the device back to ask for a refund however they are refusing to refund me as they want to ‘fix’ the issue which is unacceptable to me after a week with the device.

I am insisting on a refund. Please assist me in getting a refund from this service provider.