Asks for around £300 in return for £50000

A man who said he was a Muslim, asked if I spoke in Urdu and said he was calling from London, said his name was Kamran Ali and  asked to go to my nearest Western Union post office and give £375, by Gram, to Bilal Ahmad, UAE, Dubai.  Slowly he decreased it to £275 and then £175 as I said I did not have the money.  He said that once I give this deposit a man will wait for me at Barclays bank and I will be given a secret pin code that I can use to claim my £50000 from Barclays Bank.   He said that my £50000 will come from an Islamic Bank by cheque and that the cheque number will be 8704367.  When I asked for proof that this wasn't a scam he mumbled in Urdu and said that he was getting angry.  He asked if I believe in God and said that the £50000 prize money I had won was a gift from God.  Eventually, my phone battery died.