Bad customer service/No exchange policy

I bought 4 packs of pampers that time of black Friday. I used 1 and now realized that 4+is small and I went to ask to exchange for size 5 and I am told I will need to top up while I am taking the same thing, is just a size exchange. The manager and assistance where both rude and they were not even making sense of what is being explained. I asked for the exchange policy they couldn't even give me. Mall of africa no service at all and they don't respect the customers.