Issue was solved. If you receive another % or another number of purchases, it's not the same offer. However, our devs will see if they could improve the algorithm :)I reported this bug month ago and still not solved!
Seems like all these who made purchase recently got punished (similar to issue that you get worse and worse offers - you accept offer of 50% discount and next time you get highest 40% discount)... repeated offers obviously do not concern all players. Bug appeared as soon as I spent money on this game and you can forget that I make that mistake again!!!