Gazumped

ga‧zump  [guh-zuhmp]

British Slang–verb (used with object)
1. to cheat (a house buyer) by raising the price, at the time a contract is to be signed, over the amount originally agreed upon. –noun
2. an act of gazumping.
[Origin: 1925–30; earlier gazoomph to swindle, argot word of uncert. orig.]

(with thanks to dictionary.com)

Yes that's right. We lost the house we'd PAID A DEPOSIT & SIGNED A CONTRACT for... So angry. Can't even make sentences!
Happier blog later about kite flying.
Grumble.

Note from Pete re: housing law:

Housing Act 1987 Sec. 2, Part vii (b) 9

A tenant who has been denied the right of access to a property after a verbal or written agreement is entitled to kick the landlord in the nads. He should respect your authoritah!