Why has a garmin coach race prediction saying slower than what I set out at the beginning

When I started a guided coach 5K plan I said that I wanted a race time of 25mins to aim for. I have been following the plan religiously and I get to the last week and look on race day run and it predicts 32mins. 
what’s this all about? I thought that if I ran the plan then I would be good for the 25mins?

If the plans aren’t going to get me to my target then what’s the point of using them?