P30 not returned

Absolutely pathetic I've listed a p30 with a broken lcd and back glass for sale on their site .A courier came to pick it up and they now tell me after I told them whats wrong with the device that my phone failed assessment. I was initially supposed to receive payment for that device but instead they tell me that it failed assessmemnt and I have to pay them for the courier to bring it back to me. I'm not going to pay for the courier when it specifically said im going to receive compensation for the device i gave them and told them exactly what was wrong on the site so why take the phone if they just gonna make me pay for it to come back ?