Please provide way to file a Formal Complaint

I have recently been experiencing an absolutely horrific experience dealing with Dell to simply purchase a laptop.  I placed an order, two weeks later when it should have arrived I contacted Dell and was informed it had been cancelled, never received an email or any communication letting me know, have spoken to eight different representatives trying to sort this issue out repeating the whole ordeal at each step of the way, three different departments, two different requests for escalation, hours on calls, chat and on hold.  Today I finally gave up that anyone had any ability to do their job and placed a new order paying an additional $100 more than the original purchase.  The last person I spoke with even gave me a phone number so that I could file a complaint and the representative at that number told me I had to log it online.  No one seems to know what they are doing or how to do their jobs.  I feel embarrassed for Dell that this ridiculous level of ineptitude is even able to exist.

I would like to know the correct method to file a formal complaint with Dell please.