Companies keep sending my dad diabetic supplies he did not order and my dad keeps mixing them up. What can I do to get these companies to stop?

Helpful advice! Also, check the name of the company that's sending the unsolicited materials and call your State's Attorney's office for advice. There may be complaints on file already. I agree that ignoring this isn't a good idea, as they may send a huge bill one day saying he owes them money. Something is very fishy.
Good luck,
Carol

First check with insurance (medicare, medicaid or supplemental)company and see if they are being charge for these supplies. Check bank statements and see if he has paid or is having a recurring charge each time. Once you collect all the info. CALL these companies and demand they stop sending. If they give you a runaround throw out some words like "attorney" that will get there attention.
If you find out that he is not paying out of pocket or insurance is not paying. Dont' think this stuff is free and ignore it. Because as you know nothing in life is free. You don't want to get a HUGE bill on day. In the meantime, if you receive more supplies like from ups or fedex I would refuse to except delivery and have it returned.