They have a website at www.royaldrurylanetheatrelondon.com and it's a con - they are nothing to do with the theatre and charge you over the odds for any tickets.
They pretend to be the theatre box office (or at least they did with me) but they aren't. I reckon that's fraud.
If you do want tickets for the Drury Lane Theatre - they did Shrek The Musican and Charlie And The Chocolate Factory - then the website to visit is www.reallyuseful.com/
It's Andrew Lloyd-Webber's company and you should always buy your tickets direct from him.
Click HERE for tickets.