Speaking about haggling on price, you do that before not after the service has been completed. And if you haggled before I would have said go there then
I remember one woman come to pick up an order once and asked for a discount. I said you knew the price before you picked up and that was on the receipt. She goes but it is cheaper over there.
I said to her I don't fill my car up with petrol, then go down the road, see it for cheaper and then expect to come back for a discount.
The look on her face was like the Windows loading icon that goes on and on