Phontrader ****ming me

I sent through my phone to be sold by Phontrader. Its going onto 2 months now and I am not receiving any communication from them. I asked for my phone back but I'm not getting joy from them, No communication via WhatsApp nor on email. They said someone made an odder on my devices, twice already but as soon as I accept the offer they disappear. I just want mt device back or they must pay me for the phone.