Kellie Barclay

Ok I have wanted a b class for years and finally convinced my hubby to buy me one! Got a 2006 petrol, Guy I bought from seemed genuine but since I have bought it it takes 3/4 attempts to get it to start! It seems to start then cuts out a few times before its running! Happens after being left for 10/15 mins. Also the battery key has stopped working so having to manually lock and unlock the car. Called the guy I purchased from and he is saying it needs a computer update??? Can't find anything online! Please and advice great fully received thank you x