I have heard nothing about new ranges of numbers being blocked etc. I find the best way to contact moderators is to use the private messaging here (envelope icon up near the top right) and send a message to “Moderator_Team”. Then watch the envelope for a bubble to appear indicating a response.
Meanwhile, make certain nothing has changed with how you dial the call. Using call display on your phone if your mom called you last likely wont work as it wont have the correct access codes in front. No 1 at the beginning but rather 011. Also check your Self Serve account to be sure the International Calling plan is still there with minutes. Yes the free plan from PM last Christmas and the previous Christmas include the UK. That should be good for England, Scotland, Wales, and Northern Ireland but not the other “Ireland”.
My dads cell number has the same message as you. I was told certain codes are blocked but these dont apply to his number. I also have the uk add on. My brothers number in the uk works fine. No help so far.