I used them last year and experienced a couple of issues.
I ordered an ND2, ND4 and ND8 coking P Grad filters. order placed no problems, after a week no delivery. so i phoned them to be advised they had the 4 and 8 in stock but not the 2 but the 2 would be in by the end of the week. so i waited. Again no delivery, so i phoned and eventually they agreed to post out the 4 and 8 and I waited for the ND2, again promised it would be the start of the following week. Once again no delivery so after a total of 4 weeks I was advised that they still had no delivery and the issue was cokin who couldn't produce them quickly enough. I ended up cancelling the ND2 and keeping the ND4 and ND8 and getting the ND2 elsewhere.
They did refund the value of the ND2 onto my card so I wasn't out of pocket but I did feel I'd been messed about and not kept updated with the problems.
I've not had cause to use them since, but I think should i decide to, I'd phone to ensure all items were in stock. Delivery of the items in stock was prompt once actually shipped.