market manipulators

This is how manipulated the share market is:

I put in a Buy and Sell order of 45,000 units this morning as an arbitrage trade one at 12c the other at 12.5c

Guess what happened:

Only one trade went through (half fill for me on the buy side) hence i was left with about 25,000 units in the bid side.

Heres the catch. My order was at the bottom of the que and somehow jumped all the other orders above.

The one trade that half filled my order was a NXXXT.

The sharemarket is manipulated by these algorithms so much. This one trade somehow picked my order (at the bottom of the pile) and filled on it ahead of other buy orders in the que (knowing that I had the same amount of units on each side ie 45000)...what a joke of a market