i want to cancel the seller postaged the pack. That will be fraud.
It isn't fraud, it's what you accepted when you bought this.
Your seller is in China, and so is this welding machine. If you import items direct from China you don't get any of the safeguards you take for granted in the UK. For a start, business sellers in China are not legally required to accept returns, and the listing states that they don't do so.
You will have no UK statutory consumer protection if the item is faulty, or even unsafe. In fact, you as the importer are personally responsible for ensuring that it meets UK safety requirements, which many direct imports don't. Any warranty will be meaningless and even eBay's 30 day money back guarantee will probably require you to pay the postage to China if you have to return it.
By the way, you can expect to be charged VAT on importing it, either collected on delivery or added to your eBay invoice on behalf of HMRC.
Your experience should be a warning to others that buying from unknown sellers online, especially from the Far East, is not like the shops.
