Or if we want to go really outrageous, a division of BT still controlling literally every new home install of telephone lines, often with engineers not turning up, or not being trained to do the job they've been sent to!
I'm genuinely amazed that anyone still buys the argument that competition in a capitalist economy will improve quality. It does nothing but encourage corner-cutting, box-ticking, de-skilling of the workforce, and the extraction of revenue away from the electorate by monopolies who covertly cooperate to game the system. It demotivates, impoverishes, and homogenises. Truly dreadful.
Genuine market competition does work, or at least provides customers with a choice from cheap corner-cut option to expensive high-quality option.
What people forget is the list of prerequisite conditions for good market competition: plenty of buyers and sellers, good information about products, easy comparison, low transaction and switching costs, low cost of entry.
Fake markets for denationalised industries (I've seen this called "playing at shops") do not generally work very well because they're missing one or more of those attributes.
(Note to non-UKians: BT do, in fact, control most of the ADSL provision in the country and are still a defacto monopoly.)