Combo box in subform won't update

[TCS222]

I have example of what i'm trying to do but with big problems. I'm not a great VBA programmer so try to make Access do the work where possible but i'm going wrong somewhere here.The database holds company information with a separate table for the related contacts in the company. A third table holds information about documents raised against the company but when a document is raised, the user needs to choose the contact they spoke to from the company (there will be only one). The form frm_customer in the front end is the one that i'm looking at. The subform is created from a query. The query should filter by the customer chosen on the form but doesn't. Can anyone see what's going wrong here please? This is a put together example as the real database has lots of sensitive data. I can't seem to add the database (it just sits there adding it!) but will try again once I've submitted the post.

[TCS222]

I click add files - upload and nothing happens.. it just sits there with a circle going round and its only a small file.. perhaps its Windows 8! . if anyone is willing to take a look i'll have to email you! thanks.

[TCS222]

When I run the query that the combo box is using to display the contacts, the right customer contacts are returned. When I click the combo box in the form to display the contacts (which is from the said query), it shows random contacts! Any ideas please?