They are extremely stingy with PAD. It's just part of who they are. If you benefit from the shops with or without haggling with them over PAD then they can be a good company to work with. Mostly because they do so many grocery shops and pay so quickly. I manage to cover from 80-100 percent of our grocery bill each month.
For me I consider it beneficial if two weeks after buying groceries the money goes right back into my account.
That being said, if you are trying to get PAD for a shop you wouldn't be doing without it, I have found that to be mostly a waste of time. I was trying to put together a route recently and they had a cell phone shop in the general area that had been there for awhile. I applied for PAD because $6 is not worth me going to the trouble of parking and getting out of my car. When I route shops the best paying go in first and then I look for fillers. That particular day I had some choices of fillers and all of them were better than $6. So they didn't get their shop done because they just let it sit with the PAD request so the morning I left to do the route I cancelled the request. A few days later they emailed me with an offer of about half the PAD I had asked for (and it was very reasonable).
I appreciate them for what they do but I wait for them to contact me if they want something done badly enough and then I make my PAD requests.