Contact us
Message the shop first for anything about a specific order — they can act on it directly and usually answer within hours.
When to contact the marketplace instead
Payment problems, a shop that has not replied in 48 hours, or anything about your account rather than an order.
What to include
Your order number and what you would like to happen. "Order 10231, the print is off-centre, I would like a replacement" gets resolved in one round; "my order is wrong" takes four.