Tracing Company Ownership

Hey Guys,
Is there a legal, (relatively) simple and cheap way to (for want of a better word) investigate a companys ownership - specifically to make sure two or more companies are not connected.
I recently had some extremely bad service from a shop, I won't name them (I still have Neils boot prints on my butt from the last time I named and shamed on here) but suffice to say I'd go back to Win NT and 13.6 dialup before I'd buy so much as a $2 cable from these clowns.

Is there a way I can be sure that the other shop I will now use is not connected in any way to the shop I will not use?
Cheers
Smidsy

Do an ASIC search. It can be a bit convoluted, but you can get the basic information within 30 minutes or so.

You can do a search via ASIC, some are free and some there is fee charged

In NSW a company search to find the directors will cost, but if you do a google search for "Bumco Pty Ltd directors" (other brands are available) you will often get the information for free.