Says my Realm is expired but isn’t

I am playing Minecraft on Nintendo Switch. I bought a Realms subscription on the 15th Dec. On 26th Dec a message appeared saying my subscription had expired. It won’t let me play minecraft or access my realm (even though friends are still playing the realm). 
I tried to pay to extend subscription and ended up with a new realm (which I don’t need/want) and I still get the same expired message. So now can’t play on either realm...or even just on minecraft itself!