Debonairs pizza willows Bloemfontein

I made an online order of half and half pizza which was R199 I had a R50 voucher and I app**** and my total at checkout was R149 when I went to store and pay then collect I used my card and when I got home I see that the debited amount was R199 and when I checked the app the voucher was redeemed. Why did the cashier made me pay R199 instead of R149?