hi , @Vasileios Panagiotidis 
 

a number transfer usually takes 5-7 days before it is ready. you will receive an SMS when it is approved. But it could be that you have a binding period left with the previous operator or another reason.

But to find out if something is wrong. So it is best to contact customer service or the nearest 3 store if you have the roads by

https://www.tre.se/support#kontaktaoss

best regards , F