instruction:
Given a travel related situation, and given a specific question about the situation, summarize the question into a title
question:
A few days ago I wanted to buy Pegasus airline tickets because it was offering a 50% reduction on normal fares. I wanted a few tickets but couldn't even buy a single one. I tried different places with different networks but none worked. I even called my sister in New York to buy tickets for me and the result was again ineffective.

This is not the first time I encountered this problem. I have faced similar issues with other budget airlines as well (Ryanair, AirAsia). All the time during the sale, the website page was unresponsive. Well I do understand it all happens because of airline biggest sale promotion. I have bought promotion tickets "buy 1 get 1" and "Up to 25% off" before, but never been able to buy anything from the biggest sales.

Is there any possibility or hack to buy an airline ticket in one of these sales?

answer:
How to buy low cost airline tickets while airlines are offering big reductions

question:
I wil be flying with United Airlines (basic economy) to the US. The fight consists of two parts: One trans-Atlantic international flight, and one (US) domestic flight, all on the same United Airlines ticket.

Now, the carry-on baggage rules here state that "Most travelers can bring on board one full-sized carry-on bag plus one personal item free of charge. If you have purchased Basic Economy for a trans-Atlantic flight, you'll still be allowed both carry-on items. For all other Basic Economy tickets, you will only be allowed one personal item". Does the restiction to one personal item apply in my case? Or does it not apply as one part of the flight is an trans-Atlantic one?

answer:
Carry-on baggage restrictions for United Airlines?

question:
I have an ESTA for the US, valid until Mar 20, 2020. I have confirmed the ESTA is still valid on the U.S. Customs and Border Protection site. However, the airline I have a flight booked with will not allow me to check in online due to not having a valid ESTA/VISA/etc.

Does this mean I'm not going to be allowed on the flight or is it simply a problem with the online check-in? And if I'm allowed on the flight, should I expect issues on arrival in the US?

answer:
Valid ESTA for US, but not allowed to check-in Online