Phonetradr - stole my phone

Phonetradr has had my phone since around March 2023 , in March this year 2024 after months of trying to get hold of them, they contact me to ask for a better sale price on the phone , which I agreed too. I have not hear from then since . I have spent hours calling them , NO REPLY , I have emailed them , NO REPLY, I have whatsapp NO REPLY....... I have no idea what to do next , however whoever has purchased my phone is now in possession of ****** property. Until such time as I am paid , my phone is ****** and I will be reporting it as ******. If anyone has any idea of how to contact this company , please let me know. I trusted them as I previously sold 2 devices through them. DONT BUY FROM THEM