4 x Scissor Sisters tickets at the BT River of Music festival - Tower of London ?

Hi, I bought 4 tickets and unfortunately we cant go, its for Saturday 21st July. Its a sold out event. http://www.btriverofmusic.com/stage/americas BT River of Music: Americas Stage - Tower of London Event times Saturday 21 July Doors open at 11:00 Music starts at Midday. All start times of performances are approximate. The performances on both nights will end at 21:30. Line-up (all line-ups are subject to change) Saturday 21 July Hosts: Jason John Whitehead and Dana Alexander. DJ: Sofrito (Hugo Mendez & Frankie Francis) Soul Caribbean: Midday Roberto Pla Latin Jazz Ensemble: 13:30 Roberto Fonseca: 15:00 Jazz at Lincoln Center with Wynton Marsalis: 16:40 Naturally 7: 18:15 Scissor Sisters: 20:00