Extra Charges without notifying us Client

I'm a very disappointed Client today @ 16h01 i bought Steers @ Protea Glen Mall to my surprise i had to pay an extra R3.90 for 1000 Island sauce ,the is no sign or anything written at the store that states i have to pay extra for a sauce ,when I paid my R3.90 I was given a big bottle of 1000 island to squeeze the sauce into my packet of chips not even on the sachet ,Manager Ntombi told me its an instruction from the headoffice and dat was it..