I sure hope you can resolve the issue asap with the Transfer Agent and by that I mean before the Tranfer Agent or whoever is withholding the tax has remitted the tax to CRA (Canada Revenue Agency). Once the withheld tax is remitted to CRA, although incorrectly, it's a nightmare trying to get it back.

Technically, you'd have to file a non-resident tax return at the end of the year, with the information slip (it should be a T5 in normal circumstances if it is a proper dividend) showing the withholding tax. And since it is a 'return of capital', there should be no tax and you can claim a full refund of the amount withheld.

But going through that takes time and lots of frustration. The worst is, because it is an unusual situation and it was a mistake, it may take forever for the CRA to release the withholding tax. Good luck to you!