Yes they can - the problem I found with all my local ones is that they spot a non-diver from miles away and they refuse to fill a bottle for aviation use. I did the BSAC course part-way but could not bu**!!!!! my way through this. One of them kept asking me for an oxygen handling certificate. In another it would depend which 16 year old kid was on duty when I turned up. Some shops do little o2 trade outside the UK diving season and don't carry the stuff then. One used to do it, and then the helpful man left.
Another problem was that the American portable aviation oxygen kit bottles have a U.S. "540" thread on top of their valves. This is also a dead give-away of you not being a diver. You can buy a 540 to BOC adaptor but it's normally a short stiff one, which requires the bottle to be held up high while being refilled from the (normally vertically standing) source bottle. The dive shops don't like doing this and I don't blame them - I like to be some distance away from the bottle being filled, but not so far I can't see the gauge. I refill mine via a flexible hose assembly made specially for high pressure oxygen, but if you turned up with one of those in a dive shop....
One solution, if you have a usable dive shop, is to get the bottles with a valve which has the standard diving thread on top of it.
All too much hassle. I wrote some details down - email me if you need more info.
Bose x - you have my email.