Cub cadet specialties sent the wrong belt.

I ordered a 490489-r2 and got a 489399-r1 which is 1/2by 80 . Not happy...... my question is this belt is 80" and its much to short. I tried it and with the sdjustment pulley all the way in I still would have had to pry it on. I need a much bigger belt. It doesnt even seem like an 81.5 would work. Any help?