I have just managed to get the epdq plugin working.
it seems that the one included in 4.0.2 links to an incorrect site.
https://mdepayments.epdq.co.uk/ncol/prod/orderstandard_utf8.asp
it should be:
Payment confirmation
I have looked through these forums for an answer and thankfully barclaycard support managed to help.
hope someone else finds this useful