Problems with I-phone people

[scraggy55]

My son was sent an I-phone he did not order. We phoned them and told them we did not order it. This alone is a bit of a worry as it was addressed exactly and had proper name, address and postcode on it. How on earth did that happen. We were asked to return it and because I did not see why we should pay for special postage as it was their mistake, we sent it normal post back to them. Surprise, surprise they say it never got back to them. Now they are threatening us with Bailiffs and some company (which I presume is the Bailifff company) is calling us constantly saying they will come to the house if some ridiculous amount of money is not paid. Who should we contact regarding this? How can we prevent this Bailiff company actually turning up on the doorstep? We have tried to ring them many times and they never answer. We have spoken to O2 of several occasions and they said there is nothing they can do and that it is in the hands of this other company now. We are really concerned. Help!