Trying to Claim a Prize I won

I was telephoned to say I had won a competition and it would be delivered to me. I received the knives and the bar fridge but no 2 cases of Stella Artois. Do you think anyone answers the switchboard number??? I have been trying continuously for 4 days and absolutely no answer. I have phoned the call centre and they can't help me or give me alternative numbers. I am so frustrated. A organization as big as this doesn't answer their phones and there is absolutely no one that can assist me. Very unprofessional.