The Store Manager,
I am having a membership card of your store for almost five years (more / less) but this is the fast time I am facing this kind of trouble. On (mention the particular date) 30th August, 2020 I bought two (Mention the brand) t-shirts for me and with that there was an offer of getting a M.A.C. (any brand) mini lipstick as gift. Being (store name) it is a trustworthy shop I did not check my products after purchasing.
Unfortunately after arriving home when I opened the shopping packet I found the assured gift was missing. I thoroughly searched for the gift but it was not inside. On top of that the packet was completely sealed which was done by the store so there is no chance that I lost the freebie anyhow. I am feeling cheated somehow though I do not want to believe that as your store is one of my favourite.
Furthermore, I have tried to communicate with your store over call but did not get any response from there. Therefore, I am writing this email to convey the message to the store that I did not get my assured gift inside the packet. Please look into this matter to solve this issue immediately. I believe it is in your interest to take action on the above matter. Looking forward to your reply.
(Sender name & contact number]