1 Adult Diving for sale, 1 Adult swap for Kids ticket + Cash !

Ok this is complicated so bear with me. I have 3 adult tickets for the FINA Diving World Cup London Prepares series at the wonderful new aquatic centre, evening session on Wed 22nd Feb. The event is from 19.00 to 22.25 and has the Mens 3m Final and the Womens 10 m Synchro Final. These were meant to be for my girlfriend and I and my 8 year old son. Quite why my girlfriend bought an adult ticket for my son I do not know. My son and I still want to go so........ This is what I would like if someone can help. Ideally I would like to swap an adult ticket for a concession one, plus £25 cash and sell my extra adult ticket for £32.75 (£30 +£2.75 booking fee, but obviously this may not be possible so also contact me if you want just the adult ticket. If anyone has two concessions for that session I would also be interested. Can meet up in Hackney this w/e, the City Mon,Tues or Wed or of course at the venue on Weds too. Cheers Mark