There are some hosting companies that refuse to give any sort of refund on an annual subscription after the Money Back Guarantee period. These hosts have poisoned the well. I believe the fair thing to do it to offer a refund for the remainder of the year based on the monthly charge.
For example: Suppose I charge you $10/mo or $8.00/mo if paid annually (first payment is $96.00). If you cancel after 3 months, the refund will then be based on the monthly rate. Thus the refund I would give is $96-$30 = $66. (Pro-rated amount = $72.00)
There are other hosts, who readily admit in this thread, that its more than appropriate for them to pocket the entire $72.00 and show you the door.
See Example Their justification is that the 3 months is beyond the Money Back Guarantee Period (which are traditionally based on monthly subscriptions).
Perhaps if more hosts used my formula both the industry and the customer will be rewarded.