CNXtrans complaint: Dubious charges

I ordered a set of sofa and a set of dining table from a supplier in China which cost me a total of £1400. I then contracted CNXtrans to do the frieight forwarding for me as my shipper. To ship the item from China to UK port. They charged me a whopping £1500 for a total weight of 500kgs by sea from China and insisted I make the payment via bank transfer to their UK bank account which is in an individual account holder’s name, which I did. After 4 weeks, the shipment arrived UK, and I contracted a customs broker to help clear the goods from customs, only for the broker to realise CNXtrans has charged me an additional £2200 in the name of terminal handling documentation fees, and other fees which I have to pay before my goods are released. The broker was greatly surprised at that amount and called it ridiculous. He revealed to me that normally, it costs about £900 to ship that size of goods from China to my door in UK which includes customs and terminal handling documentation fees. Now I don’t know what to do as this is dubious and I can’t afford to make such payment. Meanwhile, CNXtrans never had a working telephone line and it takes them 2-3 days to respond to emails. These should have served as waring signs to me. Please can anyone advise me on what to do. Should I report this to the Chinese Embassy? Who is likely to help me with this situation?