For US citizen who is currently in a violation of work permit in Slovakia & EU (sent by US company)?

What should a US citizen do who is currently in a violation of work permit policy in Slovakia & EU. The US employer sent the employee to Slovakia for month to do a training job, but now it is discovered that it was the employee's responsibility to take care of immigration issues according to the company's policy which was not notified prior. The duration of the trip was for month. The current stay is 21+ days. Thank you!