Bookstore in HK

This is last Thursday incident:

I was happy with the deal I got in this bookstore chain in HK - when I bought the 3 in 1 set for Cecelia Ahern's books. But I was not happy with their service:
1. They promised a free cloth book wrap for purchases above certain amount. When we were at the counter, they did not offer the book wrap, but there was also another promotion going on, and we got a book voucher (which can only be used from 29/12 - 31/1, luckily we will be back - if not I'm going to make a complain about this too, it was not stated that the voucher cannot be used immediately or in the next purchase, what if we were not going back to HK during that period??)
2. After we paid, and before we left, the book wrap promotion caught our attention again, so we went to the Customer Service counter, who told us that the book wrapping service was outside the shop.
3. At the book wrapping counter, they wanted to wrap up the book in paper! And said they knew nothing about the cloth wrapping.
4. We went inside again and look at the promotion sign... I read from top to bottom and all the fine prints... Nothing was wrong, I'm supposed to get a free cloth book wrap.
5. Then we went to the counter, who finally admitted we are entitled for the book wrap. They wrapped the book for us.
6. On our way out, we wanted to take a picture of the promotion sign - which shows you how to wrap the book. And they did not let us to take a photo of it. I understand if I can't take a picture of the shop or the books... but this sign. It's telling you: You either get a free book cloth wrap, or you can purchase the scarf and wrap the book as below.... then the graphic image of it...

So... they ask you to buy the scarf to wrap the books, and don't allow you to take a snapshot on how to use the scarf to wrap the books... how inconvenient!!

ttg