You have my sympathy - someone had planted bamboo in my last garden and it was terrible stuff - it used to pop up yards away from the main clump and was literally impossible to dig up.

I managed to knock it back using Roundup. That got rid of some of it.

After some years it flowered and I was hanging out the flags, thinking it would die. It staggered on for several years before finally dieing off and most of the shoots went black and were dead. But I see that about 5% of them are growing back. It's the new owner's problem now :-)

so true Beattie...I have been through the wars with this