Minimax Demo a complete waste!

Absolutely Frustrated! I purchased a minimax vacuum demo from the verimark online site in October 2020. After a few uses probably less than 10 of vacuuming a small carpet the vacuum keeps switching off. I called the head office to be told to take it into a verimark store. I did just that the manager at Hillcrest Corner Durban was extremely helpful and efficient. She asked me if I wanted to exchange and I was happy to do so as I enjoy using the vacuum. Upon arriving home I assembled the vacuum to ensure its working, the dust cup clip was just slipping off so I called in the store to inform them as I never used it yet but the issued arised. Today I went back the manager changed the vacuum as she couldn't replace just the dust cup. She tested it in store and it seemed fine. I arrived home assembled it and tested it then this 1 has a horrid sound after a few minutes of being switched on. My query is why sell demo products of electric appliances that state are checked and quality control is submitted if clearly there's issues. Now to my dismay I'll have to wait for my vacuum to go in for quality control and I have no idea what the outcome will be. Bare in mind I'm highly pregnant and have to go back and forth also keeping in mind that this vacuum is 3 MONTHS OLD and barely used. I would really appreciate it if I get some feedback firstly because I only started trusting the Verimark brand last year after purchasing this product. I have also purchased 5 other products with you guys which Im honestly starting to regret incase I have the same issues regarding the guarantee. It would also be nice if you guys could provide me with an accurate turn around time as I could be expected anytime mid next month to go in for delivery of my baby and if the product lies in store I will suffer the consequences of losing time on my guarantee.