Travelling from Belfast to Dublin airport was fine. However the return journey was not. I was near the beginning of queue and a girl with a tablet was scanning codes on tickets before letting us board. There was no code on my ticket even though it was valid and paid for. She kept me back while others behind me boarded consequently I was left until nearly last and had to maneuver through the bus to the back with breathing equipment I couldn't put underneath the coach. I found this very distressing and was breathless before I managed to get a seat . The air-conditioning wasn't on and the bus was very stuffy and I found it difficult to get a deep breath. The air-conditioning which lowered the temperature was only put on at Sprucefield, that being 2 hours into the journey. A child sitting beside me felt sick and unwell. Not a nice experience