I bought a reconditioned S7 Edge on 4th May. It ar...

I bought a reconditioned S7 Edge on 4th May. It arrived fairly quickly but within a day it had crashed with a "Bootloader exception" message and nothing would work. I sent it back for repair. They told me they had changed the battery. I got it back for the second time on 17th May. within 3 hours of getting it back the same error message came up and the phone wouldn't work. I sent it back again and asked for a refund. They told me it would take 10-14 days to arrange a refund, which was too long to be without a phone so I asked for a replacement - they told me I could have replacement within 3-5 days. It is now 7th June and I do not have replacement phone.
Their customer service is terrible - they will only respond to emails and never promptly - they will not call me to discuss the issue. I have spent ages on hold to their phone line dues to there being "nobody available to take my call", and since yesterday they have simply been disconnecting my calls before answering - 3 times now I have waited to speak to someone and the line has been disconnected.
I have never had such a bad experience with anything that I have purchased