have you tried gotraveldirect.com
they are a smaller company and they use zoom airlines
they fly out of ottawa as well and i have used them many times
they only have chartered flights which mean you need to by a return ticket for a week or two but they fly into santo domingo
they can be pretty cheap in the summer
but because it's the summer things but be limited
they fly to santo domingo out of montreal all year but they only fly into santo domingo out of ottawa in the winter
