if youve cut it right down and its still sending up shoots i would get some thick black plastic and some elastic bands.id cover each stump with the plastic and an elastic band. id then put some soil over the edges of the plastic but dont cover it. you can keep an eye on it then.it worked well for me and though im not good at latin names as im dyslexic i think i have or had the same kind of hedge as you i do believe . its a real mission digging the roots right out. i hope this helps take care bye fpr now.
ps i believe there is a poison for painting on such stumps but i dont like using chemicals if i can help it .

Drill into the stumps with a medium sized woodbit and fill the holes with SBK, a brushwood killer, cover and leave.

sorted

Hi I would like thank nosypotter and Banboo for thier help. I have given them a bash and have high hopes , thanks again and happy gardening:)

your more than welcome and ditto to you to .

When you drill a hole in the stump you can also try filling it with salt. That took care of a tree size weed for me.