Woolworths return policy only applicable when suits them

I’m at vangate mall woolies lost my receipt and want to do an exchange a huge sign on the wall showing I can return with mount slip but they are refusing saying they have high returns and would need to audit the return .

I’m highly upset and annoyed as I called head office and was told I could come here now I’m told different . Not sure what the issue is skin colour maybe whatever the case I’m not backing down they have a policy and need to adhere to it .