Assuming the exit rows are now all allocated, I don't think there is very much you can do given there isn't anything to refund? Just put it down to bad luck?.....in the future, I think ExpertFlyer offers aircraft change alerts, tho I don't know how good they are (I'm a new subscriber)

What options were you thinking? Is it Long Haul or Short Haul?

I do once recall a colleague got moved from his preferred seat (picked as a BAEC silver) in WT travelling transatlantic. He went to Guest Services and (very politely) asked if there was anything they could do, and much to his surprise, they gave him an upgrade to WTP. But I certainly would not expect that to be the norm.