I'll try to be respectful and clear....
Allwinner and it's Linux code affiliate Sunni-Xi have been the source of the delay of code for Linux 4.14 Kernel for the R40. BananaPi provided you with a board in good working order that works on earlier versions of Linux code, but none of it is Debian mainline..
I have the same board, and am willing to wait for Sunni-Xi to complete the code. Why? I had the same experience with Cubieboard1, another Allwinner product that at first only worked with Andriod. That was even more challenging to get Linux working in the beginning as I had to compile it myself.
A lot of people seem to think the board manufacturer is in control of Linux development. That just not the case. You got a good board at an introductory price for developers and hobbyist. Software was to come along later.
Besides, I am sure NO ONE promised you a Linux 4.14 Kernel at the time of your purchase. SO PLEASE, try to understand who is responsible for what and try not to blame the board maker for expecting too much too soon. I am not sure where SINOVOIP comes into play as I purchased my board from someone else.
Compared to the promises that Arduino and Raspberry Pi have made, Allwinner and Sunni-Xi are angels.
If you need a board with Linux 4.14 ready to go, try an Intel product and expect to pay accordingly. You just are expecting too much too soon for too little money.