I sent my iPhone to a recycling company and haven't been paid

I checked the reviews on a comparison website and they were uniformly glowing

I recently sent an iPhone for recycling to PhoneConvert for which they have still not paid me. I found them through a price comparison site, which featured uniformly good reviews. They were slow to respond and after some chasing they got back to me saying the phone was still locked to my iCloud account; this was not the case. When I complained they offered to return the phone; I accepted, but three weeks later I haven't heard from them. I've since checked and found similar stories from customers who sent them devices and were never paid. I'm concerned I will never see the phone or the 70 I was promised.
LC, London

Mobile phone recycling is now big business and there are scores of online companies offering cash for redundant handsets. You also submitted a complaint to Trading Standards and Citizens Advice. When we got in touch with PhoneConvert a spokesman insisted it "had already been in contact with the customer as we were unaware she had not received her device back due to it being locked to iCloud. After our investigation we had confirmed we would send payment and make a claim with Royal Mail." You confirmed that they had made contact after seeing a negative review and had not realised that you had not had your phone back. After the Guardian's intervention, things suddenly speeded up and you have now received the money you were owed from PhoneConvert.