Pathetic delivery charges

I have purchased some tiles and all other building renovation materials with a company Ace Hardware in phoenix industrial park. I had requested for them to do the delivery once my building is completed and the delivery cost was discussed at R200 as I am 5 minutes away from them. I had also purchased a door which I requested for an urgent delivery the next day and was charged R200. I had called the store to have my tiles delivered and the sales team insisted I pay R300 delivery. Upon querying the delivery charge I was very rudely spoken to by a man names Abbas. He talks about principal when clearly they lack of its meaning. I have my previous receipts of the delivery charge of 200. Yes it's a matter of only a 100 but imagine how many other people are being ********** of the delivery charges. We know times are tough for certain business but don't ripped 9f the innocent who pay no attention to the charges.