It has been a while that i choose the sponsor of 9 ganes won to ve granted the bonus, bit every times o choose a sponsor i hace more than 9 games won and it always stays ay end of the season with 89% and i Jeep losong the bonus

Sent here your screen captures... Let us see what was it exactly.

Keep winning games however it doesnt move to 100% since a while ir keeps happenning

Done 9/9 win without draw or loss.

I think that to achieve that bonus you have to win in 9 successive games, and you managed 8 wins in a row (8/9 = 0.888888 ~ 89%).