KFC complaint: missing item

hi
i used kfc at manchester airport terminal 2 on the 19th august at 1302 hrs 
.
i ordered my meal and walked over to our rest room at terminal 1 to eat it but when i opened it there were no chips.
when i finished my break i walked back to kfc at terminal 2 to complain to a member of staff who told me that next time i ordered a meal he would give me a 10% discount.
i was not happy with this offer as it was less than the chips cost.
i returned to kfc to speak to the manager who told me that the next time i wanted to order that i would be happy with his offer so the next day i didnt take any lunch with me to work as i would have a kfc.
i arrived at kfc and asked for the manager who was busy and couldnt see me so i returned
later.
i again asked to see the manager who this time did see me and i was told that the 10% off my order was a good offer and thats all he was prepared to do.
i rejected this offer and told him i would write a complaint and he asked who i would complain to so i told him that i would write to kfc and he just said well go ahead then.
i dont understand how one day he wanted to put this right and the next day he was not interested at all.