Subway complaint: NOT HONORING COUPON AND TOOK MY COUPON PLUS ADDED EXTRA CHARGE

I recently purchased a Turkey Italian sub at Subway store 1396-0 address 300 North Charles Street Baltimore, Maryland 21201 at approximately 11:54 am, Term ID-Transit1A-280926.
I placed my ordered and explained to the older gentleman with the black turban on his head, I have a coupon for a Footlong sub with chips and drink for $7.99. However; once we reached the register the older gentleman with turban on his head said “he could not accept my coupon because I did not tell him in the beginning and that computer will not accept coupon.” I explained to the gentleman that I did inform him. I asked him why does this location always try to avoid honoring Subway coupons? No response from him. I informed the gentleman because you have Subway name on the outside of the building and that is what you are selling are Subway merchandise and sandwiches that he would have to honor my valid Subway coupon.

In the mean while; he proceeded to complete my transaction. Once I arrived at home, I notice that he did not honor my coupon but he took my $7.99, he also did not charge me the correct price and he added a $1.00 fee for extra pepperoni on a sub that comes with peperoni. Italian cold cut the only thing I changed on the sub was the meat to Turkey instead of the regular meat that goes on there.
I attached a copy of the receipt to this complaint.
Thank you for taking the time out of your busy schedule to address this complaint, looking forward to hearing from you soon.