Empty cylinders from store

Last night I bought 4 Sodastream cylinders - I am now paying R94.99 for one - they used to be R35 so the price has tripled in about 4 years. The first cylinder I put in this morning was totally empty - no gas at all. Unfortunately there were no measurements on the side of the cylinder so I could not weigh it. I took it back this evening and Broadacres Spar swapped it immediately without any questions. I came home and put in another cylinder and it gave us one blast into a litre and the next bottle we tried to add sparkle to - it was also empty too! I feel I can't go back to them now after swapping one already. <br> This is not the first time that this has happened - especially over the last year - since the cylinder price has gone up to nearly R100. Surely by now there should be some system put in place that prevents this from happening. It all comes at our cost, not yours. It makes me very unhappy.