Are you saying you did the job for the company you named?
If you did then i think then deciding to slag em off is very bad practise.
No one forces anyone to do a job, you quote what you want, and sometimes you'll get it, sometimes you won't.
As for price fixing, i disagree. We have a fixed minimum wage if you're PAYE don't we? Is that not an example of price fixing then? No? Then neither is a minimum rate for subbing work out.
Poaching work from another is difficult to prove. If you're sending out flyers willy nilly and you get a result from one of them, you have, whether you know it or not, nicked that account from somebody else. Or are we saying its only poaching if you know it?
Don't get me wrong, i think poaching is the lowest of the low, and pretty short sighted if you're nicking it from someone giving you work. One account won from the several he has for you that you've now lost is dumb