You can call up your EOI online and correct it. Or if you submitted a paper form, you can write in with the proper information, giving all your details, and when you submitted, to what office.
It is VERY important that everything you submit to INZ is entirely accurate. An application is the equivalent of a legal document, and submitting it is like signing to say that everything on it is the truth. What ISN'T the truth can be assumed to be fraud.
Quite apart from that, how can a CO tell whether you meet the regulations if s/he has the wrong information? S/He tries to check with Mr XYZ if you worked there, and the details of your employment, and gets no answer because there is no Mr XYZ and the place really belongs to Mr ABC! You have claimed points for x number of years of work - as you've put part-time, you will only be allowed a fraction of the points as you would if you had put full-time. These things can lead to the application being refused.