DOG ATTACKS CLAIM

I am working for some company which delivers parcels. One week ago I was supposed to deliver something and as usually I phoned informing that I would like to enter the possesion. The old lady informed me that she is at home and that there is no problem to go through the gate and meet on the doorway. I was really surprised that just after few steps from the gate the big dog run toward me and I bite me on my leg. I was trying to fight with the animal but it bite me one more time. I dropped the parcel and runned away from the possesion. My company asked me to phone the ambulance and don't worry about anything more but my insurance doesn't cover the costs of the treetment. What's more, the lady doesn't feel responsible for her animal and she even claimed to my company bacause of "the bad service". What should I do and who should pay me the compensation for the accident during my work?