Missing Key

I bought a laptop from Mr Shopper. Delivery was quick and the product appeared to be in good condition. After about a week of use, one of the keys fell out. I have requested a return and it has been picked up. Three days after the withdrawal, the website said "Return rejected" and the next day "Return completed". It's been 11 days and I don't have a laptop or any updates. I emailed them, only to be told that no faults were found. I struggle to understand this as the laptop is clearly missing a key. I am shocked at this level of customer service