Once I placed an ongoing search with II that had both international and domestic locations and I was charged the international fee.
According to II, I can change the criteria of that request without losing my "place in line." As time went on, I modified the request to include other resorts and dates, and finally decided I was not going to get my exchange.
I called II to completely change my search for a different time frame and all domestic locations. I was told that even if the criteria were completely different than the initial request, the date initiated would still show as the date I entered the original search, which they said would be an advantage. I asked if I would get a refund for the difference in the exchange fee. I was told that I could, IF I completely cancel that search and initiate a new ongoing search (which of course would have a new date of initiation as that day.)
To further complicate things, I trade in II with Wyndham points, which has a weird process that many II reps and Wyndham reps don't understand. So unless I wanted to go through the whole process of canceling my request, hoping Wyndham put my points back, then "verifying" a deposit again with Wyndham, who only keeps track of II deposits in the "notes" on your account, I had to just stay with the international exchange fee. Knowing that all those steps would never occur without my monitoring every move with many phone calls and much aggravation, I left it as it was.
Back to the OP's question- if II charged you international mistakenly, then YES, you should get a refund. If you had international destinations requested, but confirmed a domestic location, then NO, I don't think they will refund. If you cancel your international search, you should get that fee refunded, then you can search again for domestic locations for that fee only.