I have been successful 10 times out of 12. There were several of us trying on multiple devices. This year was the second failure and we fell victim to being unable to buy as a friend was through to payment and it crashed waiting for confirmation. I was in 10 minutes before it sold out but the system wouldn't let me proceed because they were reserved in his order. It sucks and it should be better but hey ho. the system is possibly as good as it could be and there are other festivals to attend.
No point being bitter about it. There is a saving grace that we know in October that we have failed leaving plenty of time to find an alternative. Yes its a great festival but festivals are at least as much about the people you are with as they are the actual festival. Find something else. Trust me, Glastonbury is not the be all and end all. Maybe if the general populous realised this then tickets would be easier. Its no longer just a festival. Its the place to be seen to be attending and unfortunately that is to its detriment