Cash only for prepaid electricty, airtime etc

Stopped at Spar in Plumstead on my way home, bought some electricty, produced my debit card to pay, was told by the cashier that prepaid items are strictly cash. I said fine, leave it. Another male cashier next to here basically demamded I go and draw cash to pay for the electricty.... I said no, he called the manager who said its ok I can leave. Now, Spar in Bergvliet is where I always shop, where I always buy prepaid airtime and electricity and pay by debit card. Same applies to Spar in Rosmead, they too accept debit cards for prepaid items. So why the heck is Spar confusing matters by having one store accept debit cards and another declining them. ALL Shoprites, ALL Pick n Pay's, ALL Checkers accept debit cards for prepaid purchases... C'mon Spar, get with the program, either decide that debit cards are accepted (or not accepted) by your stores and apply your decision to ALL your stores.