Lee,
This matter ultimately comes down to an issue of false advertising as part of civil law. Affinity's discount persuaded me to purchase the app. I commend your good intention for everyone to receive the discount, but it did not happen.
To follow through with good intention as well as good customer service for the company, you must honor the price advertised as regulated by our governmental agency the Federal Trade Commission as it is illegal to falsely advertise in most countries; how about the UK?
I paid $49.99 and expect to receive a $10 discount. You advertised it at that price until July 23rd. You took my money on the 23rd, so you should be able to refund $10 back.
The FTC makes such laws in order for companies for prevention versus punitive damage. However, I am looking for resolution in terms of the company's honor.
Thank you for your attention to this matter.
Kristen