Roll printing using Classic CC to Epson SC P5000 ?

I have Lightroom Classic CC and an Epson Surecolor P500 printer with a 17" roll facility, and use a Mac Pro OSX El Capitan

Using the roll paper option, whatever size I select, and whether I choose portrait or landscape, it will only print the narrow side on the 17" side of the roll. For example, if I choose A3 size I am wasting 5¼" x 16½", whereas, if it printed as I want it would only be using 12" off the17" roll.

I have sent now 17 emails to Epson who cannot sort it out & who say:

“We can´t give support on aspects we don´t design or develop. This issue is being caused by the software and settings that determine what is printed. The printer and driver is simply a slave to the software you´re printing from".

Adobe Lightroom support say "Printer settings are the responsibility of Epson"

Any guidance would be most welcome, as I am wasting rather a lot of money on this poor response.