I understand they have a "shelf life" as it were and don't go on forever. However I don't know how long lived they are.

I had one that died exactly the same way, took me 2yrs to actually get the stump out, however I now have 3 new ones that appeared a good 3ft away from the original trunk, one has even come up in my neighbours, the roots had gone under our separating wall, luckily my neighbour likes it......I think my original was over 10yrs old........

I agree its a shortlived shrub, maybe the wet and windy winter wasn't to its liking, cold its roots have been flooded at all?

Average life expectancy of these is around 12 years, but sometimes they live much longer - or shorter, maybe 7 years, luck of the draw to some extent. Sometimes parts die off but other parts are still alive, but often that means the shrub is lopsided or badly shaped by the time all the dead stuff has been cut off.

Check whether there's any life anywhere and if not, heave it out, if you can, if there is life, cut back what's dead and see what it looks like.

Hi Kabkev, we had one when we lived in Brittany for ages, must have been ten years, on moving back to Tipton it started exhibiting the same symptoms as yours. A neighbour took it under her wing and gave it some intensive therapy, involving much organic mulching and a lot of garlic compost. In the end I got a sharp pair of shears , chopped it all up into fine pieces and threw it on the fire.