TMART U.S.A no phone numbers only e.mails Sold me a UV gel curing lamp, Internet

I bought a UV curing lamp for my wife, It cost 32.90 and eventually arrived 20 days later when we received it, it had a continental  switch and on the box it stated 100-120V on the side of the box also below that 220-240V below it with two white boxes presumably to tick for voltage but with nothing on them with a picture of the unit on the whole box.I went and bought a converter switch for6.99 and plugged it in, within about 5 minutes there was a tremendous bang and the unit went blank.

I e.mailed the company who was in China which was on the delivery package and they e.mailed back what country i came from, even though my address was on the package and they then wrote back and said they only supply these units in 100-120V i then wrote back and and said about the two voltages on the box and they said they would correct the boxes. I could write a book on this with letters flying back and forth, but the final crunch is even  they would not give me my money back there company sign says 90 day money back guarantee .I have sent a posting to facebook under TMART complaints signed R.Lambert94 and still have a useless nail curing box in my lounge. I have told them i am taking the unit to our trading standards in England,and the box has a CE logo on it but coming from China possibly a false sign.