Had Americas Tires install new tires BIG PROBLEM

If I'm reading correctly it's just the gray tank drain. If so there is probably no need for insurance. The line is just standard black ABS that you can buy at Home Depot. Call a mobile repair guy to come out and repair the line. If it's readily exposed you could also call a plumber as well. I'll bet the repair is under $200 when it's all said and done. Hopefully the manager will pay up if you can present an invoice and avoid the hassle of small claims court.