Especially this time of year where the stress of working in retail at Christmas is stacking on any current tech trends (like this new mining obsession).
Also ringing them up will mean that you will deal with whoever picks up the phone and may not the person who knows the answer, whether they are there or not (they may be busy elsewhere or dealing with other customers which is likely). Posting on the forum in the customer service section will let the people who know the answer, get back to you when they have time, rather than giving you a half guess at that instant, which could bite you on the ass later.
I posted the exact same question on the 290x release, as the premium for fitting a card wouldn't be justified if i had to fit it myself anyway to get the backplate on. Turns out you dont need to take the block off but OCuk offered to do it for me without charging extra or me offering to do it for them.