Legal advice about work situation (Wiesbaden-Mainz)

My Spanish husband has been working in Wiesbaden for the last 3 years. He has broken the meniscus in his knee and come back to Spain, but he broke his knee at work, the Doctor in Germany said eh could come to Spain to get the operation and it was all right. Now the restaurant has sent a letter that they have terminated his contract. He has not been paid anything since he left Germany.
Does anyone have a contact I can use to help us sort out his legal/work situation. His only friends were others who work in the restaurant and none of them wants to lose their job by helping my husband.