Bought machine for kitchen with problems no help manager

Dear Sir and Madame: This well-considered letter is to bring your attention to the horrific experience with my latest purchase, a brand new mixer at your store last week. I was very excited to get the BM500 mixer thanks to the amazing reviews I have seen from my research. Although the payment and delivery process was such a breeze, the shipment came with a little damage on the side of the box. When I was going through the set-up stage, the machine worked fine with the lowest speed. However, it was impossible to switch it to a higher speed. Regardless of the time and effort I spent following the user’s manual instructions, I could only turn it on with one mode of operation. As soon as I stumbled on the problem, I made a call to your assistant phone line, looking for some help. While the gentleman over the phone was very nice and patient to talk to, he provided me little to no help in fixing the issue. All the information he provided was already there in the manual and such level of service made me question myself about choosing your store for further purchases. I have been a very loyal customer of your store since I moved to this city, and I am very disappointed with the poor assistance I have experienced. I think as a manager, there are many options for you to fix my problems, but I would like to ask if you could so kindly arrange an in-person device check-up for my newly bought mixer. I really like this model so in case if your experts could not fix it on the appointment, would it be possible to provide me with a new unit? Please seriously consider my complaint for immediate actions to be taken. Kind regards, Thien An Huynh