I know that in a salary discussions, I need to make the points about the value I provide to the company and not to compare myself to what is happening with other employees.
Making people aware of your value is important, but ultimately it is a comparison of yourself to others on a single point; and much like a MPG, km/L or L/100 km comparison of motor vehicles - is that the only reason to buy a particular car?
Maintenance is important (they ought to maintain wage and bonus with both the cost of living and what other companies are prepared to pay, not how little your co-workers are prepared to accept).
But what can I do if my manager does exactly this and tells me that "compared to other employees, your salary is high at the moment". I have no way to verify this, as our contracts prohibit talking about the amount of our wage.
In reality you have no way to compare unless you actually see their paystub and job-shadow them for a period of time. If the manager doesn't know you should get more and you know you should then someone's mistaken; if you improve your future there or elsewhere it won't be your mistake, if the company won't budge on that you won't advance (in the company or your life, becoming richer for your efforts).
Many times I've been somewhere inquiring about employment and got the chance to briefly question a random person walking by about working at the company: The worst case was the reply "It's a job" (but the pay was not awful), and the best answer was "We make good money here" (when in fact they hadn't been paid for months), or vice versa.
There's some very distorted reasoning about what makes for good value.
Does the manager have a good point?
I think that the manager's point is "you're not getting any more money" obviously that's no good for you.
I've worked at places where the manager has gone to visit the owner every week, for months, to plead with the owner to fire someone whom was damaging equipment and bringing the work to a halt - every day two others would have to work half their shift to undo the idiot's mess and put things right - there was simply no way, no chance, that the owner would fire the person, they kept their job for years. But other people would ask for a well deserved raise and not receive it, unsatisfied that they were paying to keep a few unproductive people employed they quit; and the owner was only too happy to see them go. The owner simply thought backwards.
The way some people perceive value is a mystery sometimes.
What is important to you:
Can you eat and pay your bills.
Can you walk across the street and earn significantly more.
If you don't have any recourse then you don't want to be too vocal until you have another offer locked up. If you've been there a while and ought to have brought up bonuses or a raise sooner (or they ought to have offered you one) it's in your interests to be the one to keep track of that - it's rare for a company to say "we don't pay you nearly enough, here's a big raise".
Don't accept the excuse that the company isn't run profitably or that others work for too little without complaint, unless that's your fault - get what you can get, there or elsewhere.
I've found that you actually have to have one foot out the door before they realize it's not the cost of keeping you, it's the cost of you leaving.
Compare how many times you've had to ask for more with how much practice the manager has had with telling people "no" - see: he has more work experience than you.
If you are being taken advantage of and getting poor excuses then polish up your resume, interview elsewhere discreetly (don't tell them where you work), and lock in a better offer (or even an equal one with less travel time, or easier work, better advancement opportunities, etc.).
The puny chance that the company has no more money for a great employee is slim, the better chance (and the manager knows it) is that people will stay for too little far too long, and as long as they think you're replaceable there's no more money for you.
Replace your employer with a better one, someone who values your work and respects your 'proof of value statement' that clearly outlined how you've benefitted the company. If they're doing you a big favor your job is in jeopardy, and you will need to look elsewhere either way.
You know how to do your research (search here or elsewhere for "how do I know ..." or "how should I ..."), as long as you can go somewhere else (and your resume doesn't show a history of job hopping), just go. Don't accept that weak excuse when you have better options.