Help Please....Anyone??

Aug 15, 2017
My friend had an iphone 5 on O2, last year she changed to a Samsung S6 on Vodafone. She wanted to keep the number and she was able to transfer it over. No problem there!! But...and this is a big but... her calls and texts still go to the iphone which has a sim in it but no contract at all, and if she wants to call, text or browse the web she has to use her Samsung. Both O2 and Vodafone are saying it's not their fault, and Apple Store is saying it's the network providers.
Does anyone else have this problem at all?? Or can anyone give a reasonable solution, it's beyond funny now. Thank you in anticipation. Jules