Greenwich - Peninsula - chenandolo Review

I work for NHS and ever since I started going to Nandos I have been getting discount as I always have my NHS with me. I was very disappointed when I attended this branch where I was told that I couldn't get a discount unless if I buy another meal which I find it very wierd. I bought a meal platter to share and a portion of livers. I've never been told something like this ever since and the manager Padimin with guts insisted that I can not get my discount on this receipt, unless I buy on a different receipt. Is this how we will be treated becouse if we don't deserve such a good will why advirtising in our work place when we can not actually get it in your restaurant. Can you come back to me an explain if there's a different form of ID that we are suppose to present when ordering or is it only available to specific type of people as I feel like just becouse of how I look it's the reason I was refused to get a discount which shouldn't happen in any of your restaurant.
Looking to hear from you