Updated a contact but Messages isn't updating it

I used to live in the UK and had a UK sim card. I moved to Portugal and got a portuguese SIM card on my iphone. I updated my contacts to have the country code before the number, but whenever i try to text any of them, it doesn't work.

I have credit, all other portuguese contacts work, and the ones that already had the country code before also work. I have tried to add both numbers to the same contact (with and without the country code) and it still doesn't work.

Maybe deleting the whole conversations would help? But I don't want to do that.

I would appreciate any ideas.

Thank you