To answer your question, yes, I would keep the 'I wish'. However, I would also try to shorten the sentence to make it clearer and to make it easier to read. What do you think of this:
I wish to obtain a position in order to contribute my skills and help the center exceed its target for superior customer service .
There is no need to write: "...within an existing or new call center..." since you are (I imagine) going for such jobs, which makes this statement rather redundant.
I, personally, would not say this,"...where I can enhance my experience...", simply because employers tend to think in selfish terms as far as recruiting is concerned. They want to know what's in it for them.
"...meet..."? No, let's reach for the stars! Just say, "exceed". That's good.
"their" or "its" - it's up to you.
Call centre/center? Goals? Surely the primary goal is (as you nicely put it): "superior customer service". And I suggest "target" in this instance rather than "goal".
Hope this helps.