mislav:Well, the volume of the 15 liter tank doesn't change with pressure, what you do is you squeeze more air into the same volume. In Europe and Egypt they normally fill the tanks of any volume up to the 200 bar, so I believe this to be the standard procedure, not something to be disappointed about.
I think I didn't make myself clear, mostly because of the fact that 15 litres imply volume not amount of air compressed in tank.
It is VERY disappointing. The volume doesn't change but the amount of air does and that is the whole point of renting a larger tank. I am not renting a larger tank because I like the bigger size but because it can hold more air! Yes I still get more air with 15 litre tank filled @ 200 bars than I do with 11 litre tank @ 200 bars but I would not in any way accept that here in Vancouver. All that is made worse when they argue with me that the tanks were designed to be filled at lower rate than what is stamped on them.
This happend to me on two trips and that's why I'm determined to take my tanks with me and leave them there. They will still fill them with no more than 200 bars but with a 17 litre tank that's a lot of air still.
With regard to the heat thing and cooling off. I get my tanks filled regularly in Vancouver and the dive shop is familiar with filling steel tanks. I leave them overnight and get them next day @ 230 bars or more. That's called professionalism.
Having said all that, I contacted the the dive shop a couple of days ago and was told that they simply don't have compressor that can fill tanks more than 200 bars. They said there are a couple of shops in Sharm who can fill up to 300 Bars but that would be costly for them shuttle tanks back and forth to fill them properly.