But as is the norm, probably better (and maybe necessary before complaining to such professional body) that you complain in writing to the other party.
Civil engineer-unfortunately he has been made aware that he has been entirely unsatisfactory in his dealings & has refused to respond to any letters of complaint
In that case you should contact 'Engineers Ireland' as mentioned previously by 'Banking2006'.
Even if the engineer is not a member they may be able to advise on what to do next.
If you are an individual consumer and the engineer has not delivered whatever service you paid for, you could consider a Small Claims Court case against him.