Order over the telephone and stipulate that you want a +2. If they can't promise that its is, buy elsewhere or get an undertaking from them in writing that they will pay for it's return if it turns out not to be a +2. Great play is made about service levels at OcUK, so hold them to it.
That said - I was in-store on Saturday and two guys came in and asked to see a case - they were told that boxes were sealed and could not be opened in store. They left. I have no idea how many sales are lost like that, but it's obviously not enough to make them change policy.
I'm a great believer in caveat emptor, but this stuff about we don't open the boxes and our suppliers are not able to tell us what's in the boxes ("drugs you say?, well I never!") is just unacceptable in my opinion. If I turned up at a customer with a copy of SAP R/3 and I said 'SAP just ship these brown cardboard boxes, I don't know what version of the software is inside' - they would quite correctly show me the door. Customers expect to get the latest version of something and to pay less if the version is not the latest.