Unreliable and rude - the sales managers will hang up on you
I made a flight booking on travelup. I got an email confirmation saying my booking was successful. A little while later I noticed there was no charge on my card despite the email listing how much I had been charged. I called and was told that because I'd never responded to an email asking for a bank card security code (a. which I'd never received, not even to my spam folder and b. who does that via email?), they'd cancelled my flight booking. They had never even sent me any correspondence to tell me I needed to provide any info, or even that they had cancelled my booking! When I told a manager this on the phone he just HUNG UP on me! Never again!