Doing a wedding shoot three weeks ago, I either lost or had stolen a small bag, that contained some small items, one such was the external microphone holder that you can take off with two small screws, I did this and put it into the small bag as I needed to take it off at the time.
Now I cannot find the bag anyway and need to use the external microphone holder for shotgun microphone for the next wedding coming up shortly.
Can you purchase these online (I have searched the Internet and nothing comes up) or do I need to call Canon for a replacement, that is, if they do sell them separately from the camera?
Thanks.

Canon sells any part for the camera. All you have to do is call and order it and give a credit card number. If you're in a hurry you'll have to pay for overnight shipping.

You might consider a camera shoe shock mount like this instead:

Beyerdynamic | EA86 - Camera Shoe Shock Mount | 407186 | B&H (http://www.bhphotovideo.com/c/product/108256-REG/Beyerdynamic_407186_EA86_Camera_Shoe.html)

We had to replace one, it is part #DG3-1754-000, was $45 as I recall it, and it doesn't come with the screws, so if you lost those too, tell Canon you need some...hth...Battle Vaughan Miami Herald.com. video team

Thanks for your help guys.
Well I have managed to get one.

I first telephoned Canon UK and they passed me from pillow to post at first and then finally gave me a telephone number to contact a third party dealer ( H. Lehmann: London) who has spares and repairs of Canon cameras & Camcorders.

They have sent me one and it's true the tiny screws do not come with it, however I had put the tiny screws in an envolope for safe keeping and still have those.
It cost £25.00 ($36.61) + Vat £28.75 ($42.11)

If any one requires the two small screws the part number is Da3-5272-000.