My plane was delayed by 24hr so I tried to extend the stay using the "manage my booking" feature online however everytime I clicked this it redirected me back to the log in page which was very frustrating. I decided to ring instead and was able to pay 10 pounds to extend my stay quite easily using my credit card. However when I tried to leave the airport it wouldn't let me out saying I owed 19.50 pounds. I couldn't reverse out of the barried area without blocking the road so had to abandon my car while I went back into the airport to try and use the machine inside. When I tried to used this it said I owed abour £250 (by the way only one machine worked out of the two and seemed extremely tempremental). I went back to my car where I rang back the customer service who directed me to the gate house. After 10 minutes of explaining and some phone calls the man at the gate house was able to resolve the issue and let me out (he did a good job). The whole process was quite stressful especially as I had been travelling for over 16 hours after being delayed 24 hrs at the place I travelled from. It was the last thing I needed and could have been prevented if the person at customer services had done their job properly and processed my payment correctly. Also your internet manage booking feature does not work which would be far the easiest way to sort the booking out espescially for people operating on different time zones.