Despite nearly 18 months to run on his contract, Cas has expressed his desires to return to his homeland and his young family.
After a meeting with Groves, the decision was made to terminate the remaining 18 months on the contract. Cas however is now refusing to sign the release forms until he has sorted himself out with work in Holland.
"I told the gaffer about my situation and then we had a bit of a fall-out. We don't get along," Cas told the Grimsby Telegraph.
"If your head's not normal then you won't work right. If the gaffer asks for my opinion then I'll give him it.
"The club told me that if I'm going they want me to go now.
"I've played my last game for the club. The manager knew on Saturday against Plymouth that it was my last game and he didn't give me the chance to say a proper goodbye to the club and the fans.
"I apologise to the fans for not giving them a proper goodbye. I had a very good relationship with them even though I wasn't playing every time.
"I think the gaffer has lost all hope in me after Saturday and he wanted me to sign the papers yesterday. But I'm not signing anything until I've heard whether I've got a job fixed up in Holland, becaue I have my mortgage to pay.
"I have to get fixed up with a job and I'm waiting for some people to get back to me. If they do, I'll go in tomorrow, sign the papers, and go home at the weekend."
Cas added that he clashed with Groves and doesn't like him. Amazingly he goes onto state that despite his 'awesome' form he was not given a fair chance in the team.
"When I came here my agent told me it was a good club and this and that. Then I came and found out it was exactly the opposite," Cas continued.
"I enjoy it with the lads and they are a great bunch. But I'm 31 and I still want to learn. I haven't learned anything here.
"I played in the first 10 games and thought I did pretty well. But after my injury I never got a chance again and that's rubbish.
"I played 10 games awesome and I didn't get any credit for that. I'm a right winger, not a right back.
"The manager didn't like me and I don't like him.
"At this club, the players are okay but that's it. There's no fun, you just work your socks off.
"There needs to be some fun at the club and that will help the players work harder for each other."