We got our letter last month just before our trip to the UK. We went into the office today and they didn't even ask our name, they told our interpreter that it's all now been sorted out, everyone can remain in the scheme and the only change being that if you are a married couple and both in receipt of the state pension then you need to register separately and both will need to pay the monthly premium.
So in a nutshell, if you've had a letter requesting you attend the office, just ignore it.