Discount of 7,50 suddenly reduced by 25 cents

For whatever reason I cannot start a new thread, so I'm just latching on to this one

Up until now I've had a discount of 7,50, but suddenly this month it was reduced to 7,25, and I cannot find any explanation anywhere.

The itemization on page 2 used to say:

• KPN Internet 100 Mbit/s 42,50
• Actiekorting eerste 6 maanden -7,50 

But now says:

• KPN Internet 100 Mbit/s 42,50
• Actiekorting eerste 6 maanden -7,25

25 cents isn't a big deal, but I find it curious that I cannot find an explanation for why the discount stated in our signed contract has changed.

Admin: helped turn the question into a new topic. (original)