Any place that I can take oversized clothing and downsize it?

Yea. A tailor. Look in your Yellow Pages.

People often suggest a dry cleaners but in my country they are very expensive. I usually go to an alterations place. But the work you want done may add up to a similar cost of just buying a jacket that already fits.

yep it's called a tailor

Yes, there are loads of shops that do clothing alterations, sometimes combined with other businesses like dry cleaners.

Check Yell for your area.