Leaking dr brown bottels

<p><br />Good day, I've bought a starter pack wide neck bottels and find it was leaking, so I bought a twin pack as well but the same happened. I'm really struggling with my new dr browns bottels. It's leaking constantly!! I've taken out the vents, hope it will be better but it's worse. It keeps leaking at the ***** / thread of the bottel neck. Can you please assist me in the return policy or what I can do to prevent this from happening? It's really frustrating and a hassle. Regards Linda.</p>