The online complaint form is nothing other than a classic piece of obscurantism designed to enmesh the plaintiff in a circular morass of non-ending emails or phone calls that never get answered. Most of the emails and replies to this page are from an inactive email address and advise the recipient to sign in to their support page.
Unfortunately this is the best you get from a company with millions of customers, if you want better support and point to point contact procedure you will have to sign with a provider that offers this.
These companies often cost more but the level of care and dedication reflects that, however you will later find that because everything is running fine you will question the price you pay based on the fact a equivalent level of service (ie. the speed) is available from the bigger and cheaper corps.
Currently the complaint form for Virgin Media is very overused due to the fact that Virgin's customer service availability has shrunk considerably means its become the only source that people believe they can use.
Does this need to change, YES but being that its nearly been a year of 'special measures' and Virgin seem to not be interested in doing what other providers have done to alleviate the pressures on its 'operational' (UK) team so guessing the issues will continue until the outside branches of the support service come back online and good old game of catch up starts.
During this time, customers will need to choose to either bide their time and work with what is available or leave for better.
My main account where I need to reliability and support (if needed) is now in the notice period and actually no longer in use (I've left)