charged for tests not done, cant resolve or even answer query

I have being charged for a test I did not have. It is not the sort of test one would forget! I suspect other tests charged for at the same time may be related to this test but Lancet cannot or will not answer my query in this regard. Lancets stock answer is that your doctor ordered the test therefore you must pay for it. Despite numerous attempts to sort this out there seems to be no one at lancet who has the ability or perhaps authority to resolve this and I am now been hounded by persons claiming to be their agents, threatening to blacklist me. Surely Lancet should be required to prove these tests were done on me before being allowed to blacklist and or hound Me? This is a brief summary of the problem and doesnt even begin to address the incompetence of their accounting operations.