Oil Change

I received a birthday coupon for a discount oil change, I went on a sat to get it done, they told me that they only do coupon M-F I made a appooinment for the following Tuesday 8:30am I showed up when they saw that I had a coupon on my hand they told me that they didnt have any appoinment under any name for that time, the guy behind the counter didnt even bother to look it up instead he searched on a scratch paper and said nope I dont have your name here, then he told me that they only accept coupons on Wednesday, I think they send coupons at home to try to get you to come in, and hopefully get you to paid full price by telling you they dont take coupons that day you are in.