I have a 2013 Ford B Max got from a Car Sales March 22 low mileage 49.000 miles. 
I don’t do a lot of Miles it’s only on 54.000 miles after nearly 20 months driving. 
been very reliable no issues. 
but last Friday I set off to get some petrol. It was on red and I may have pushed this, but no alerts on Car, only the marker to say it was on red. It started fine and I drove up hill on a small cul de sac, reversing, I noticed that it was troublesome putting into first gear, but nothing untoward, it started to shudder a little going down hill, as I turned the corner it died a death. At this point I presumed I had run out of petrol.

I got help and filled with Petrol, I put 5 lites in it. Tried to start up still wouldn’t work. I thought it’s the battery, but still couldn’t get it started, called out recovery in my insurance he tried charging it, but still wouldn’t start, he dropped off at my address, he said it’s the battery but just needs a longer charge. 
What charge I had in the car by the next day it was depleted. 
my son tried to help on the Saturday, got more charge into it, but it reved but just wouldn’t start. He doesn’t think it’s the battery, after two days I still can’t start it, but lights work radio, and trying to start it is still the same it just doesn’t seem to fire basically 

Is the battery holding charge now?  If not, that needs to be replaced before going any further.

If it's not the battery, air may have been sucked into the fuel pipes.  If you can, remove one of petrol pipe connections under the bonnet.  Then switch the ignition on and see if petrol flows from it.

Just to rule out the obvious - are you 100% sure petrol was used?  Not diesel by accident?