Bought an iPhone from here. When it finally arrive...

Bought an iPhone from here. When it finally arrived after around 10 days, It was ok for a few days until I noticed that the GPS wasn t working. I have since sent it back and quick mobile fix are saying that they haven t received it yet despite it saying that it s been delivered on Royal Mail s website. No one ever answers the phone - all I ve had so far is an email to say that they haven t received the phone yet, well someone s received it so what happens if they just say it s been lost?? Avoid this terrible company at ALL COSTS. Update: it s now been 10 days they have had the returned phone. Still no refund. Whenever I email I get a rude response saying it has to be 10 working days and then how many working days it has been. Shocking company.