Lady Gaga standing tickets want to swap to seated tickets or sell at the price I purchased them at *

Have two tickets for Lady Gaga on the 15th September would like to swap for seated tickets or sell at the price purchased with ticket master which was 200 euro. My son is now unable to go and unless i get seated will not be able to take my young daughter as they say children need to be seated and so will I to be able to survive the whole concert. Will be able to arrange collection/delivery thanks