I need to report a glitch on the 360 version.

I am not sure where to report this, but I was playing Forza Horizon 2 on the 360 and I unlocked the perk where you get 25% more credits for completing events. Instead of 25% when I completed the Amateur Division however, it gave me 999,999,999cr. I need to report this, but I don’t know where to report it, so here it is.

I am getting internet soon and do not want to connect online if this is not resolved, because I do not want to be banned. Can anyone help me out?