Hi Michal,
Thank you for taking the time to leave a review! I'm sorry to hear that your experience hasn't been what you hoped with your flat back studs and the pin tension issues! We'd love to see if we can help further. If you reach out to our customer service at hello@cordsclub.com or chat us on the Cords Club website (little pink and white icon in the bottom corner), we can help you further.
-Kellie with Cords Club
“These are the best. Such cute dainty earrings, they are so comfortable to wear. They can be tricky to put on so but they applicator or get creative. Also they do not come off in your sleep.”