Competitor delisting my product by placing fake orders

I am selling a product on a listing that is not restricted. However a competitor keeps placing large orders on my listing to make my product out of stock. So far they have placed 49 orders totalling over £1mil. Amazon saw a sudden spike and deactivated my account even though I reported this. I understand that Amazon have to do their checks and they have now reactivated my account. Amazon told me action was taken against competitor but can’t give me the details. However the competitor has done it again. Placed large orders so I’m showing out of stock. Forgot to add the orders are from a Business account and just stay in pending for days. Also, was receiving threatening messages from competitor telling me that they will get a service provider to close my Amazon account. Has anyone else been through this? I don’t know what to do.