Why is there only one monopolies commission?
The Monopoly and Mergers Commission is a government body designed to ensure that a given market sector does not act anti-competatively due to monopoly or oligarchy. As such, there is only need for one.
And why is the word abbreviation sooooo long?
Sharing a Latin root with 'Brevity', abreviation is a verb form now used as a noun. The correct meaning is 'To shorten'. Since this word is not an abreviation itself, why should it be shorter than it is?
I fear simple mis-application of logic has lead to your misunderstandings. I trust this has helped.