With just over three weeks until Cyber Monday, Amazon's busiest shopping day of the year, some suspended sellers are finding it impossible to get reinstated in preparation for the holiday rush because of an apparent glitch that's keeping them offline.

Third-party merchants, who account for the bulk of volume on Amazon's marketplace, can get suspended for a number of different reasons, often having to do with infringement claims, legitimate or not, from rival sellers. To get back up and running, they have to go through a reinstatement process.

But sellers who are trying to contact Amazon about a suspended account or product listing say they're being redirected to resubmit their appeal through Amazon's Account Health website. That method also fails, resulting in sellers being sent the exact same emailed response.

Here's what Amazon is telling them:

Hello, This is not the correct channel to submit your appeal. Please resubmit your appeal and relevant information for reactivating your account by clicking the Appeal button on the Account Health Dashboard. For reactivation of listings, please visit the Account Health Dashboard and click on the Appeal button next to specific violations and complaints in the Product Policy Compliance section.

One Amazon merchant, who has sold consumer goods on the site for the past decade, told CNBC that he spoke with an employee from Amazon's Account Health support team who confirmed the email was a bug that first appeared on Wednesday. His account was suspended last week after a brand filed an IP infringement complaint.

The seller, who asked not to be identified to preserve his relationship with Amazon, was able to settle the complaint with the brand and submitted a plan of action, which is a necessary step to get reinstated. That's when the message arrived from Amazon, saying the seller was not using the "correct channel."

The merchant said the Amazon representative indicated that, if not for the glitch, his appeal would have been accepted and his business back online.

In a statement, an Amazon spokesperson said the emailed response was not due to a technical error and added that the company encourages sellers to file their appeals through the Seller Central portal. But the spokesperson didn't address why sellers who submitted their appeals through Seller Central were still receiving the technical error.

"There is no technical error. Some sellers whose accounts have been deactivated due to policy violations have tried to appeal their suspension by sending information to an Amazon email address rather than following instructions that we have communicated that they should submit their appeal through Seller Central, our web portal for selling on Amazon," the Amazon spokesperson said. "If sellers send appeals via email, we are providing an email response redirecting sellers to make these appeals via Seller Central."