Dealer can't fix slide out and warranty running out! HELP

Keep all the paperwork and notes on the repairs.

Go take a video and pictures of it not being repaired properly. Do not accept it and make sure everything is emptied out of it.

Demand they call the Manufacture to pick the unit up from the dealership and send it back to the factory to repair.

Keep calm, be professional and write down in your notebook as you are talking to them.