Ok. U are right. But I don't think you getting angry will impress people from Blackview.
In my case I had similar "support" with samsung.
But exactly for this reason i boyght my bv6000 from a local vendor. No trouble yet... But we'll see.
If you carefully study how everything is assembled I think it's rather easy to only change the speaker on your original back cover.
It's normal that you wish to have better support (i'm with you on that one), but for an item bougt on ebay or ali... I'm surprised that there is even this level of support.
Of course if Blackview wishes to grow as a company, and get to have a good name, they should find ways to improove both their quality and their support.