快樂牛郎

I agree with dmnf.  Who cares about the title if your pay doesn't match up.  There are a lot of cases where people are just given inflated job titles with no real responsibilities.

And finding a job in today's market is VERY easy.  There are millions of jobs that are unfilled.  You just need to have the right skill set to match them.

hotaruu

In an IT industry, I would suggest you to stay and get OT pay. I personally don't really look at the title of other people when I interview Software Engineers. All I care is what they have done in previous positions. If you can explain to your future interviewers that you are doing more than what you are ask to do, that's a plus.

快樂牛郎

titles are for people with no real skills, so they need something to dress them up

Nox

Maybe just consider taking the title with no pay for now.  The reason for that is to legitimately make your resume look nicer with that new title.  Meanwhile, start looking for other job, start sending out resumes.  I highly doubt that your employer would expect that you take the title with a smile but screw them afterwards.

With the new title, you can argue for better pay AND the title you deserve elsewhere.

example from ad agencies, if you are just a junior designer, even if you have the skills and experience, it's hard to ask your new employer to give you a higher position with better pay.  But if you get raised to senior designer, you can back that with your portfolio and force your new employer to put you in the senior designer position.  (They don't necessary have to know that you've been in the senior designer position for only a few months, all they usually check is that you indeed work at such and such location as such and such position, if it's real, it's good enough)