Haven't had this problem myself yet with Bosch SDS & 75mm tile-removing
chisel from Screwfix, but I must admit I've only used it so far with vinyl
tiles (very tough ones, in my defence!). Assuming we are talking about the
same thing these chisels cost £29.99 a throw (c.f. a fraction of that for an
"ordinary" sized SDS chisel) so they damn well should be fit for purpose.