False adverti*****t

I got a cellphone with them and it had an adverti*****t that if you purchase it you will get a R2000 accessories voucher. First they said I needed to reedem it online, then they said they can't give it to me because it was a claimed cellphone, I mean how does that work because I could have chosen to take my money from the claim and not buy any cell but becaus3 the offer was enticing I decided to choose the cell with the voucher. Their working method is always changing.