I booked a ticket to Pisa, Italy from Gulf Air . The flight which I booked had a stop at London (Heathrow Airport) as per my visa (Type D schengen visa) I don't require a transit visa for terminal change (This information I got from UK visa regulations in UK govt site). On the day of travel airlines people didn't allowed me check in telling that I require a transit visa which is not required. I invested a huge amount, I lost it. My course started 2 months back am already late. It has heavily impacted my studies. When I contacted airlines booking office regarding my concerns they were not ready to hear me and didn't clarify my doubts. Since this is affecting my studies kindly treat this complaint with higher priority.