Exchange at a price

This was to be a complaint but has been corrected. I purchased safety bots for my staff when BE were running a promotion. I have has a change in staff between purchase and handing out (2 months ago) I returned 2 pair for a size change and was asked to pay R100 a pair for the price variance. When about to walk out with the same boots they were exchanged at no cost. Thus may complaint has become a compliment, to a degree. Thank you