Winner didn't get the prize

I played a competition in March, was called and informed that i was the winner. The prize was VIP experience. it went all quiet thereafter until i received an email in July where it was stated that there won't be VIP experience anymore but i would be given a cash prize. They asked for my banking details and sent some documents to fill in. I did and sent them back. The Person who informed me about the cash prize and all that is no longer responding to my emails, there is another one who i communicated with via whatsapp and the last time we spoke she said their finance department promised to pay end of October but until today there is nothing. No communication from them. I mean it's more than six months and i do believe that their finance department was well aware of the competition when it took place but the stories they come with are just not holding water. Yes it's competition prize but i think that they must just fulfill what they promised me. I hope they will respond.