Not to be trusted

I sent my Samsung S8 64gb to mazuma after I had upgraded my phone. The phone was only 3 months old as it self was an upgrade. theY quoted me £130 for the phone. I sent it and the next day I had an email stating it was dead and no power fault and they were amending the payment to £10!!!! I called them which took 40 mins to get through and got cut off 4 times. I opened a support ticket and the adviser said it was dead but passed the battery charge test. ( I have the transcript of the chat) I explained that is not a dead phone then and I asked him to explain how it was dead and he couldn't/wouldn't. I then finally got through to the customer services and sent the pictures I had of the phone fully charged and working the night before I sent it and pictures of the phone 5 mins before I sent it with all the documentation. they would not have this and said the technicians report is correct. I have read reviews and this is not the first time they have done this. They will offer you a great price first then find a way to lower this. on this occasion they did not anticipate me having photo evidence of the phone working, fully charged and in good condition. It now looks like Mazuma report the bad reviews to get them removed. check there facebook page at the comments. there are 100s of people with the exact same story as mine