Well you could start buying the cnc shock towers and chassis braces
http://www.smddirect.co.uk/parts-328/option-parts-336/hong-nor-343/x3-rtr-options-375/
Are these Toro Esc's any good?
These seem very good value for money but anybody tried them??
http://www.ebay.co.uk/itm/131314075881?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
The Royal Mail regulations specificity prohibit sending LiPos on their own so it's a case of if the post office you go into actually knows the regulations then they won't accept them. However there are a lot of POs that haven't a clue about the regulations and happily accept them.
Just buy a Hobbywing SC8 Waterproof.
Sounds like your Castle is dead.
I fried two esc's because of water, I always get the waterproof one's since . SC8 , Quicrun etc..