Walk Behind Lawn Mowers

I have a LC 221A walk behind mower which was purchased in June 2018 and the rear plastic door which lays on top of the grass catcher has made 2 small holes in the bag from rubbing
on it when bagging grass while mowing. I believe this is a design flaw. How do I get a new grass catcher or can I get credit for this model and pay the difference to move up to a model without this rear door laying on the grass catcher since I believe the problem will continue due to this design flaw.