New Core- why is it so bad ?

As I understand it your new NextGen network/new core (used by all new eSIMs, and what looks like new physical SIMs) is based in Sweden and hence will suffer from terrible latency when browsing from the UK. I also note you don't support HD Voice - how is any of this Next Generation ? Looks more like previous generation/cobbled together to me!
Please tell me you have plans to host this from the UK (to reduce latency) and offer proper HD Voice - otherwise I suspect a lot of customers will be off to TalkMobile when you force them to migrate to the new core.

Not old SIMs? Biggest issue for me is the continuing not spots arising from being still tied to just the Vodafone network and not the combination with Three. Mobile signal in our rural county is way too patchy to non-existent and needs to be a priority for investment by Lebara

Not old SIM's yet, but this https://www.lebara.co.uk/en/fmnvo/ordersim.html suggests the plan is to move us all onto the new core at some point - would be greatful is Lebara can confirm the timescales for this, and like I said is there a plan to improve the new core before forced migrations start, as technically what we are being asked to migrate to is a step backwards.

I also agree it's a shame we can't use Three as Vodafone coverage is pretty poor since they have turned off 3G (I spend long periods of time now on Edge). I don't think this new core move is going to offer us access to the Three network, as that is a host MNO-Vodafone decision - and is something they only seem to offer via TalkMobile and Voxi.