The company you worked for on the agency will need to keep records of the hours you worked so all companies that employ agency drivers usually download your digicard at the end of the shift. If they didn't download yours, then they will need to do so. The comment above is probably correct, they will withhold payment from the agency until they have the information. I suggest you go and let them download your card, as it only takes a few minutes, job done, and you get paid.
