Corey Haim Funeral -- The Ol' Switcheroo?

The company that donated money to help pay for Corey Haim's funeral stopped payment on the check it sent the family ... claiming the money wasn't being used for Haim's funeral at all.

Startifacts, a celebrity memorabilia company that had been auctioning some of Haim's stuff, had donated $20,000 to cover funeral expenses.

But after a series of back and forth emails with Haim's brother-in-law, Mark Alexander, the company learned the funeral had already been paid for by the funeral home -- and its money was going to be used for Corey's mom's cancer treatments.

A rep for Judy Haim, Corey's mom, tells TMZ Judy's medical bills are completely covered and she has no idea why Alexander gave Starifacts the wrong idea. Haim says the funeral costs were indeed all covered by the funeral home's donations fund -- and she was raising money to reimburse them.