How can I extend a border in calc?

Hello. I have created a border for my spreadsheet document, in landscape. It is just a price list of items.
I would like now to make the table longer so that I can add other items that will show within the bold line border.
I have tried dragging it, which didn’t work.
Windows 10, Intel Premium, 64 bit OS.

Please upload an .ods type sample file here.

kiss answer: as the bordered range has more than 2 columns / rows you can insert rows or columns with selected cells staying away from two top rows and two left columns, doing so will extend the frame,

perhaps you have to reorder some other items / formulas after that, just move them, the references are - mostly - correctly tracked by calc,

if your content ‘touches’ ‘the wall’ you might consider a small empty ‘helper column’ and ‘helper row’ at right and bottom of your sheet for future work …