I have also been challenged by the owner of Spar when i went into Raja regarding using the cash machine at Spar. I was met with a barrage of abuse by the owner, this was made a little worse because I had my little 5 year old boy with me.
It seems to be a tit for tat game and little childish to put a sign in front of the Spar, saying this is for Spar Customers Only, this seems to have more potential for accidents on the main road where people who park in the car park can no longer turn round, and therefore having to reverse out onto a main road as the carp park is effectively half the size.
My last comment on this is when are the the Railway Pub going to put a sign in there carp park saying Railway Customers Only, as the owner of the Spar constantly parks his Silver County Hire Van in there car park
Seems very much like the "Kettle Calling The Pot Black" as the saying goes