This is classified as a price adjustment. if you go to the store one week and buy something and then 2 weeks later you go to the same store and see that the item you bought 2 weeks prior for less, should you be entitled to be refunded the difference?
it is no difference when it comes to PoE, you purchase a micro-transaction on Friday for 220 points. Sunday that exact micro-transaction goes on sale for 167 points. should you be refunded the difference?
The answer is No. you paid what the price was at the time of purchase. stores and sellers reserve the right to change the price at any time. if the price of a monthly licence had been increased to say $10/ monthly I would not see the same complaining as your monthly price would be grand-fathered at $7.50 monthly until such time that you missed a payment at which time it would be increased to the current amount at which the bots monthly fee woud be