Do not use them! Sent my iPhone 6 to them on the 1...

Do not use them! Sent my iPhone 6 to them on the 10.04.2018, and still not received payment for it, have tried to email however had an automatic response that was for customers who had bought phones not that were selling them. I just want the money for my phone or my phone to be returned to me in the same condition it was sent to them in.
Name Adam Roberts
Order number - BD6CB4