I really do wish a Mod would sticky a statement at the top of every thread section. Even better, add a line to the sign up page for the forum. Along the lines of...
Any safe, trusted and insured site / shop in the UK will ONLY fill a bottle (air or Co2) if it meets 3 criteria. They are;
1 - It has a European safety stamp in the form of the PI mark.
2 - It is within the test date, which MUST be factory stamped on the bottle. (Or laminated in the case of a retest).
3 - It meets with the site owners approval.
If your bottle, or a bottle you think you want to buy does not meet with the above - don't buy it, use it or bring it to a paintball site.
Point 3 is of course entirely at the sites discretion. They may stop you from using a bottle which has a deep scratch, a dent, a loose reg, a bent fill nipple, smells of WD40 or it's ilk or has been repainted - one of any number of reasons really.
Just remember: Don't argue it. The only reason that is truly important is that the site is telling you that 'this' bottle is unsafe for the protection of it's staff, it's customers and you !