How to get Undermine reward

Last event character event with Kleya, my progress got stuck on, and I didn't get the reward. This time progress didn't even move, staying 0/40. So I will not get rewarded again. I contacted support. They said they will pass this to developers, and closed thread as not to be fixed. 

What is the purpose of the quest and that can't be completed because of technical issues? Why paying money for this?