I'm sorry to hear you're having some problems with your mobile number since switching over from EE, this is strange.
Can I ask how you knew that your existing number had ported over to us? Were you able to receive calls from friends/family when they called your 'EE' number?
I would also like to check if you have an iPhone, as once you change your number, you will need to update this from the phone settings so that your iMessage, Facetime calls ect will work with the number you brought over.
If you have access to your online mobile account, what number is stated from there please?
I received a text some time ago advising I needed a new SIM and needed to reply with my postcode. I've only just seen this message and am now unable to respond to the text as all sends fail and it appears I no longer have a mobile service. Can you advise how I get this situation resolved?