Joline, tricks and tips never work properly (or for long) and I would not use them. You have 2 options here: either choose to ignore them or seriously try to take them down.
You can try emailing the sellers (see SOPs for ‘cease and desist’ templates) to ask them to remove the offers, but seller to seller communication is not allowed by Amazon and almost all emails are blocked by Amazon.
If you believe they are selling counterfeit products, then you need to prove that to Amazon. The only effective way is to do test buys and take photos of the goods you received. Then ask Amazon to take down the counterfeits offers by forwarding the photos as documentary evidence.