The Seinfeld episode where actual "banning" took place was when Kramer tried to return bad fruit at Joe's produce store.

Kramer get's banned by Joe...

Then Jerry goes into Joe's for Kramer and tries to buy plums with the red on the inside, mango's and plantaines, and Joe knows the fruit isn't for Jerry, but for Kramer.

So Jerry get's banned by Joe...

So George goes to Joe's and buys several sacks full of fruit for Kramer and Jerry.
George mentions that he wasn't going back there again because Joe was watching him
very closely when he was buying the fruit.

I love watching Seinfeld. Never get's old and is still funny to this day.

Sealclubber had it right, sorry...had to go back and read all the responses
and saw that he had already posted it.