this is a result of two severe winters, the last one particularly. Check all the trunks from top to bottom - you're looking for soft, soggy, oozing, rotting, smelly, blackened areas, anything like that. If you find there are several, some near the base, you must cut the whole plant down below the lowest bad area. You say you already have some new shoots - this means they'll grow on from the roots present in the soil, but if the trunks have rotten areas, they have to go. Protect the new growth this winter.

Thanks the main stem is fine, but where the plant has split in the past its spongy to touch, also a new split has completely rotted,
working on it now taking off all dead leafs and rotten stems

can you recommend a good feed for it I,m in Essex our soil is very clay based and limey

Doesn't need anything much, copes perfectly well in ordinary soil. You can rake in some Growmore or fish blood and bone at the base if you want to, but only do it once, don't repeat.

Thank you, I have been giving it miracle grow twice each summer, once in May and again in August

I will get some grow more and rake it in, Many thanks

If you have general purpose Miracle Gro already, then use that - but don't feed past end of June (and that applies to the vast majority of plants in the garden).