Last Saturday the special marbles were on sale from Fr. 20. I wanted to get these for my son to complete our collection. Unfortunately we were very disappointed. I read in the flyer that the marbles are available from one purchase. But I can't see from the description that only one ball is available per purchase. Now we have only received the blue one. So there is no possibility to exchange. I don't think this is right as I have also bought for over CHF 100. Unfortunately, these marbles were only available last Saturday. So we will never be able to complete this collection. I can't explain this to our son and make it understandable. We are very sad about it.