Hi Dollydee
I can't find it in the news feed - so I'm not sure what you are referring to. If your PIP has been extended until March 2021 you would expect to be reviewed about 6 months before your end date which is exactly now. If you think the letter has been sent in error - then you need to get onto them and ask or be ready for an assessment at 2:15 today.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems