For us over here there are a few places that fill bottles but they all only do 232bar. The one I uses has just charged me £9 to fill a 15ltr, 10ltr and 3tlr bottles.

All I do is give him a ring a few days in advance and arrange a time to drop them off, he does diving as a trade so not always there. Once dropped off arrange to pick the bottles up 5 or so days later and at a approximate time. Bottles are then left in a location ready to be picked up.

He gives us notice of when the bottles are nearly due for test and we can arrange through him for them to be done. I believe that one of our local gun shops charges £1 for a rifle to be filled.