Disappointed customer

I have an account with Lewis Middelburg Mpumalanga , on the 19th of August I received a call and text from Lewis telling me that I must come and collect the gift valued at R500, I went to the store on the 22nd of August I 2as told I need to buy first in order to get the gift but on the text they said one is not oblige to make a purchase but to my surprise the store told me that. I then called the customer service and told them what had transpired they invistigated and called me to collect the gift from the store, I went to the store to get the gift, the value of the gift is R20( measuring s****/cup), imagine I use R90 to get to the store only to get gift valued R20. Later that evening I got a text from them saying thank you for your resent purchase of which I honestly don't get it. The store failed me as well as the head office I am so disappointed