"The Connector-Pipe's the wrong length @##%$**!!!"
.... Can anyone relate to this? (I want to hear your story)......

The above attachments illustrate a (brand-new, fresh out-of-the-box!) 'TAIFU' (Chinese brand) ejector-head in the attempt to assemble it. The first photo pretty much says it all: the venturi discharge-end projects 18mm above the end of the connector-pipe. The second photo shows what happens next: the standard fitting will only engage barely 3 threads before bottoming-out on the end of the projecting venturi, i.e. it is physically impossible to do it up properly (note the amount of exposed thread). Any attempt to force it will only crush the venturi and risk damaging it. The third photo is staged to show how it should appear if properly tightened.
The measured length of the supplied connector-pipe is 161mm and by my calculations, should in fact be 178mm.
Although in my case the brand is 'TAIFU' I wouldn't be surprised if this ejector-head is a generic type supplied with a variety of other Chinese-origin brands.
I am interested to hear if anyone else has encountered the same problem and whether your story ultimately lead to any resolution with your supplier e.g. warranty claim due to deffective goods, etc.
I suspect that my case is only the tip of a very large ice-berg and I want to gauge the magnitude of the problem. I do expect however that there may be a lot of engineering-illiterate idiots who have foolishly installed this in their well not appreciating that the connector-pipe is not done-up properly i.e. in service; leaking/loss-of-prime, risk of joint separation, premature corrosion of threads.
Looking forward to your replies.