Durable Medical Equipment Companies

Does anyone know how to get big box DME companies to treat you with respect and get your needed equipment to you in a reasonable amount of time? Loved going through MiniMed and Dexcom directly but recently my insurance didn’t renew contracts with them so I have bounced from one terrible company to the next that are in network with my insurance… This last round it look 6 weeks to get a new Dexcom system. I have hypoglycemia unawares so I start feeling low when near 20. So this is a necessary device for me. I was on the phone daily with Edgepark and they dropped the ball over and over again. Is there anyway to advocate for yourself against these giant companies that have terrible customer service but we have to use due to insurance?