Great game but keep getting f*** over

So Ive had this game for a long time I loved it and would consider it to anyone but recently Ive been trying to get the new dokkan event the ssgss vegito and I spend a lot of dragon stones on this banner and gotten nothing but Rares and SR and I dont think its fair and its rigged. I used around 250-300 dragon stones on the banner and gotten nothing but crap, pls fix this I understand that its supposed to be hard to get but it should be more available though. Its getting ridiculous

Liotel gastill about DRAGON BALL Z DOKKAN BATTLE, v3.0.1