I have just bought Forsaken DLC last week for $39.99 only to find out that they're bundling the Annual Pass with Forsaken with the same price following the new expansion announcement. I have submitted a ticket to Blizzard support but they told me that they could not issue me a refund and let me repurchase the new bundle as per policy that I have leveled up my character past level 32 and have finished the Forsaken mission. What to do?
Nothing you can do. You can't get a refund and there are no price adjustments for sales that haven't even happened yet. You just had bad timing if you wanted to save some money. But on the bright side, you have this whole season to play Forsaken rather than waiting for the next DLC and be way behind on content.