All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.
If the company specifies a hotel for its employees to stay in and to dine at the hotel restaurant provided that each of them will bring an invoice from that very hotel, then it is not permissible for the employees to agree with the hotel to add extra sums to the invoice which the employees did not spend in the same hotel, even if they spend this money in another restaurant. By this addition they lie and commit treachery. The proper thing for them to do is to explain to the company that they do not want the food that is offered by the hotel restaurant. This is what would address the problem.
Allaah Knows best.