Green’s Dictionary of Slang

(UK juv.) something unpleasant, unfair, disappointing.

1953		G. Willans Down with Skool in Complete Molesworth (1958) 8: A chiz is a swiz or swindle as any fule kno. [Ibid.] 10: He said he could do it any time pappy but did not feel like it toda chiz.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 181: The new lamentations [...] ‘chiz’ or ‘chiz-chiz’ (cross between chisel and swiz?) [...] What a chiz!