I believe that the official public tender process is designed to stop this type of discrimination, with any unlawful manipulation being viewed as a criminal act. However like many things it doesn’t mean that it never happens.
If you intend to challenge the award of a particular tender then there may well be a process for this, however I would think that you would have to have pretty water tight evidence to bring about an investigation.
Others may well know a lot more then me on this matter but in the absence of any other posts at this time, I would suggest that you try looking on the DTI site or contacting them for further information.
If it was simply a private tender then I am not sure you can do anything.