I feel cheated (repost from other blog)

This may or may not be fair, but nevertheless I feel cheated.

I have subscribed to "Locus: the magazine of the science fiction & fantasy field" for several years. The magazine is sent to me from beyond the pond, by sea mail. Consequently I get each issue weeks after its publication date, but at a reasonable rate -- a rate further reduced by subscribing for two years at a time.

And then this turns up in my inbox:

Dear International Subscriber,

We value you as a subscriber and hope you are enjoying your magazine subscription. Earlier this year, the US Postal Service announced they would be raising their rates. With this rate increase came major unannounced changes to their entire International rate structure. International surface mail (sea mail) and international periodicals mail were discontinued. Without those two mailing services, we can only fulfill subscriptions by airmail.

These changes affect your subscription and all of our other international surface mail subscribers. We will be converting all our surface mail subscriptions to airmail. Current Canadian and Mexican subscribers will lose one issue from their periodical rate subscriptions. Our current International surface mail subscribers will receive two airmail issues for every three remaining surface mail issues. If you have any questions, or would prefer to receive a refund of the remaining balance on your subscription, please let us know. Our rates will be going up for first class Canadian subscribers on July 1, 2007. If you renew before then, you will get the old rates.

We are sorry to have to make these changes, we hope you understand why the conversion is necessary, and we thank you for your continued support.

Best,
Locus

I don't know. I agreed to pay for two years in advance on the understanding that I was securing 24 issues at the then current rate. I appreciate that Locus could not have foreseen the end of sea mail. But suppose there's a hike in the cost of paper, or printing, or another increase in airmail postage -- will they feel able to charge me for those as well, on my current subscription? If so, what's the point of paying two years (or more) in advance?

I haven't done the sums, but I hope the offer of cancellation doesn't mean I'll have paid more for the issues I've already received than I originally agreed to.

Not that I will necessarily opt for cancellation. As I say, I haven't done the sums.