Failure to provide petrol

Hi
I went into Harwich -Dovercourt petrol station approx 1 and half hours ago and filled up my Honda Civic with £10.01 unleaded petrol, my tank was low but the fuel light had not yet come on. I know £10 at the cost of £1.87 provide just over 5 litres however driving away to Clacton Essex I noted the fuel gauge had not not moved and 5 mins outside Harwich the fuel light came on registering 35 miles to run, until empty.
I drove the round trip to Clacton to drop my son off and then back to Harwich. Fuel consumption was clearly ok and I was not losing fuel. Upon arrival back at Harwich I proceeded straight to the Morrisons garage in Harwich and filled up with £20 of unleaded petrol at a price of £1.87 per litre- the fuel gauge went up to well over a third full and not far below the half way point on the fuel gauge. It then registered 145 miles empty.
It is now clear to me when I filled up at petrol pump number 3 at BP Harwich I paid £10.01 for absolutely no fuel delivery whatsoever.
I declined a receipt when I initially paid by cash but the petrol station attendant remembered me when I went in to complain , advising me that maybe with 5 litres,it would not have gone up much if tank was empty. It was not empty and the comparison with Morrison at similar pricing leads to me to a clear conclusion your company failed to deliver goods that in good faith I paid for - which I believe to be wholly unacceptable and unjust.
You have taken my money and provided no goods.
I will never be buying fuel again from BP , and will advise all and sundry of my experiences to ensure they have as little faith as I do in the ability for your company to meet its obligations to provide goods upon payment.