Different refunf policy

I bought a VW Polo BAH thermostat at Voslorus branch at 9H15 on Saturday 02 March 2018 then I decided to return it same day at 13H30 as my thermostat housing had a thermostat already. They refused to refund me saying instead I should take something else. I’ve been to East Rand Mall branch where they will just refund you without any hustle. This Voslorus branch is even charging higher prices than any other Goldwagen.The sales assistant even called the owner who refuse to refund me.