Spar till points

I have been to spar in jeppe and rissik street johannesburg cbd twice and on both accounts i have been told i cannot puchase airtime or get cash back at till points the disgusting thing is that the staff do not even explain why i past complained to the manager about this but seems it has not been handled yet.

Today i was told i cannot purchase airtime at tillpoints without an explanation the manager did try to assist but my card wouldn't allowa me transact at the spark atm fnb.I then went to shoprite and did get assisted with the transaction i wanted to do at till points .

May you please explain why cant we buy prepaid airtime or cash back with our debit cards at this spar.