Message not delivered - but only to one specific user
My girlfriend has just purchased an Iphone 5. She is on T-Mobile in the UK.
I have a Samsung Galaxy S3. I am on Vodafone in the UK.
Here is the problem. I can text her (SMS message) but she can't text me back. If she tries, it sends and then she gets 'message not delivered.' This happens whether she sends me a new message or replies to one of my messages. She can ring me, however. Other people with Iphone 5's can message me without a problem, and she can send texts to others with no problem.
I checked her settings and she doesn't have me down as an Iphone. We've deleted my contact details and put them in again but still get the same result.
She rang T-mobile, who said it was Vodafone's fault. I phoned Vodafone, who said it was Samsung's fault. I rang Samsung who said there was no way it was their fault and was most likely a fault with the Iphone 5 as there are lots of posts on the internet about this.
However, I have found no answer.
Can anybody help?