Serves you right for buying Raymarine!!
You should be able to enter coast station MMSI, both for and individaul call and in your memory.
If you can't contact Raymarine and rant.
If you can't do it the radio would seem not to be up to spec.
we do enter all the coast station MMSI's in to the memory.
We flet it was a helpful thing to do.
They can be change by the end user at any time.
I found another radio last that did not allow you to select the type of distress you are in, very iffy IMHO.
Not sure I have been much help but well worth a call to Raymarine to ask how and why.
For any one looking for a new radio LIBS will be well worth a visit!!!