Thanks for your suggestions and support. After rather a long stay in hospital (I went in for a couple of days, but actually spent most of January in hospital, as I got an infection in my bile duct, then got dehydrated, then got another infection in Gall Bladder, but all is now well) I'm now home again and loving being here.
In the end after several discussions we decided:
1. Not to put more metal stents inside the first ones (as what happens after another year or two? - we can't do it forever like that),
2. Not to just leave it - as it would clog up pretty quickly anyway,
3. So the only option left was plastic stents inside my metal ones. This is now done, and all is working perfectly. The only problem will be after 3 months or so when/if they block, as they'll need replacing again. However this should be an ERCP thing, not a stabbing, so less intrusive.
There is another option we discussed, which uses a new bit of technology to clean the inside of the metal stent by cutting away all the cells and stuff sitting there. As this is still new (at least here in my part of the UK) it's a bit experimental but sounds like it could be good. Also done via ERCP so not intrusive. Will keep you posted as to what we do next - but it will be a while or so yet as for now all is working fine.
In the meantime thanks again for your thoughts - and enjoy every day!