I have been asked to chime in on this, so here goes -
It's been said thousands of times on this board, don't match the job title, match the job duties and responsibilities. But it IS very difficult in this case, given that the corresponding project title is listed with this NOC, and some NOCs are really broad and/or poorly written. I always recommend that the letter contain a couple of sentences about what the company does, who the clients are, and your role in the company, to give sufficient context (that hopefully corresponds with the lead statement).
I agree with Amisnic, the NOC and duties in the LOE don't match. It's hard to tell whether you have the wrong NOC or whether your LOE is the problem. I will take your word for it that it's a higher level job, but when I searched for an NOC that matched the duties in the LOE, this is what I found - construction schedule co-ordinator (Note that this is NOT my field - same situation as the VO).
http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/ProfileKeyword.aspx?val=1&val1=1523&val11=construction&val12=0&val13=0&val14=&val15=0&val16=0
In some ways, you sound a bit like a business consultant - NOC 1122 is usually the catchall for other QC/management consultants
http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/ProfileKeyword.aspx?val=1&val1=1122&val11=management+consultant&val12=0&val13=0&val14=&val15=0&val16=0
Project managers/QC positions in other occupations are usually a skill level A job (not O), so this makes it even more difficult to convince the VO that a Level O NOC is suitable. You could make that point, that there are no Skill Level A occupations in the NOC system for major group 7, and "middle managers" are included level O occupations - see the matrix -
http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/html/Matrix.html)
So - if you are 100% certain that 0711 is the "best" NOC, then the following are options:
1) Do nothing, wait for 2nd review and allow the senior VO to do his/her job. If they also have concerns, you will have the opportunity to explain.
2) Get a new letter of employment that better describes what you do (or did) and the level at which you do it, so that a layperson can understand. And note, that "manager" to CIC means managing people - if you supervise anyone, or have training and/or hiring/firing responsibilties, ADD those to the letter.
3) Provide a written explanation as to why you chose that NOC and how your position corresponds to it. (If you describe duties that are not in your letter of employment, it will be meaningless). Highlight which of the duties in NOC 0711 correspond to yours.
I would not change the NOC to the engineering NOC, as the duties don't match.
Note that you can TRY to "change" or convince the VO that you made an error, or explain your choice, but there is no guarantee that it will be accepted (worse, sometimes it can backfire).