Disappointing service

I have been shopping with Absolute Pets for a while now and as a perk for being a member, you receive a birthday gift for your pet upon any purchase. In the email it clearly states that there are two different codes, one for in-store purchases and one for online purchases. I placed my order online and used the correct code, but upon collection of my order in-store I was refused the gift and was told I needed a different code to receive the gift. I was not purchasing the goods in-store, I had bought the goods online and followed the correct procedure, so why would I need a different code upon collection? How ridiculous, I am not impressed.