Nandos Loyalty Card Rewards?

[Esmee.]

Hi, I'm a little confused about the Nandos Loyalty Card system in the UK and was wondering if anybody could help me out. I'm visiting on Tuesday and I have 3 green chilies on my card. Does that mean I'm due for a 1/4 reward chicken?

I've searched around on the internet a bit and it seems you're supposed to claim the chicken on the 3rd visit (when you get the 3rd stamp), but surely that means you're paying for your chicken in the first place?

On my 3rd visit, the girl on the till didn't mention anything to do with the card to me when I used it. My order went through as I would expect (I paid around £12 all together, normal for me). When it came to the table I recall the meal being bigger than expected. Do you think its possible the girl put through my normal order, then added a 1/4 chicken on top of it without asking me if I wanted to use it? If so does that mean I've 'wasted' that reward?

Basically what I'm asking is will my next chicken be free, or from your experiences, has the girl used up my reward without me asking for it? I don't visit too often, and get pretty anxious about stuff like this. I hate causing fuss or problems at tills (social anxiety, dont ask). I'm really dreading having a problem there on Tuesday, hence asking you guys in advance.

Thanks.