Hi Mike1950,
The law is very clear- mobility wmawards for DLA or PIP can not be increased after state pension age. If you are retired from work but not yet able to receive state pension, as you are not old enough, then you can ask DWP to review your mobility award. If you are receiving state pension then I am terribly sorry, but you will not get any upgrade on whatever mobility award you currently get.
This law has been in existence for many years if not decades, it is nothing new.
I apologise if this answer is not going to help your situation.
LL26
Nothing on this board constitutes legal advice - always consult a professional about specific problems