How can I successfully contact luxury clothing platforms?

Hi, we want to place our Clothing Brand on some platforms. There are a particular platforms for luxury brand Clothing with multi brand on it, These platforms we are targeting has no direct email or contact. Ive been contacting cuatomer service for a year but no success. Can i have some advises or idea how can be successful to contact them?> > Thank you.

Hey Rich

What are your objections from setting up your clothing brand on Shopify?