Agency did not pay for the work

[northernladyuk]

Most agents require evidence that the client has signed off the time worked.

That may indeed be their 'requirement' but it doesn't make it a legally prerequisite enforceable. If the OP did two days work, then the OP should raise an invoice (has this even happened yet??) with the contractual payment terms clearly stated, and if it isn't paid,the OP should start dunning.

The fact that the OP appears to be a tool is probably irrelevant (unless it is also an indicator that no actual professional services were delivered which is a whole other story).