Re: extra for mayonnaise: sandwich was €3.99 but was charged €4.24 after mayo added.
Out of interest, was it the "On the Run" deli that are at all the Esso stations Same thing happenened me there. I asked for a wrap and she put one slice of turkey on it. I asked for another and when I got to the till it was over €5. I asked why it was so expensive and she said it was another 95cent for the extra slice of turkey. I told her it was a rip-off and left it there and walked out. Her jaw was on the ground.
That was about two years ago so it's probably more expensive now!