Did the service technican (who didn't find the fault), replaced a cable that wasn't faulty, wired your cooker directly into a 32A outlet? and then charged you? Have i got that correct? I would be looking for my money back from the service guy, that's shocking.
Yes in theory you could replace the cooker switch with a fused spur up on the wall, but you won't get one in that double size format. Is there a 6sq cable coming from the cooker switch, which is then joined onto the cooker cable?
Power off breaker, un-wire from the cooker switch. Put a plug on it and plug it back in.