Anyone else getting users complaining of Emails with Attachments not getting to the intended receipient using smtp.vodafone.co.nz ??

What I'm getting is a user on and Exchange server that uses smtp.vodafone.co.nz as their outbound relay - When they send an email with a word document attached its not getting delivered to the end recipient. I initially put it down to attachment rules at the recipient but he can't send it to me either?? I have a spam filter I administer and the email isn't coming in at all.

1) - The attachment is only 4MB.
2) - If I set their exchange server to use MX record delivery to my domain I do get it ok
3) - I can see in the exchange message tracking that the email is being handed off to the smtp relay.
4) - I get no errors back

what makes it stranger is when I send a bunch of PDF's they came through fine but word documents don't seem to make it. All I can think of is some sort of attachment policy gone wrong on Vodafone's relay servers?

I tried ringing them and sat on hold for around 20 minutes before getting a call I needed to take - They indicate call volume is high at present.

I have to say none of it makes a lot of sense - I'm going to double check a few things like a DOCX with a DOC extension and see if its a spoofed extension policy but any policy stopping delivery should send a bounce back to the sender?

Regards,

Matt