How can they say inflation is 2%?(for UK readers)?

Where do the mathamaticians get their facts and figures only yesterday a product I buy on a regular basis for 65p had gone up to 89p ( I was told because of milk prices rising) my gas/electric has gone up 15%...because of the wet winter my vegtables especially onions have gone really expensive...so how can the Government give out such low figures telling us thats the inflation...