ETD Discount Tire Center cheating sales

I brought a 25% oil change coupon to ETD at Lyndhurst. The store manager offered me a free upgrade which worths $10. After I confirmed it is free and I acknowledged the upgrade. When the work was done and I was still charged $10 more. I asked the store manager "You were say it is free to upgrade but actually it is not free at all, right?". The store managed answered "Technically!". What a dishonst shame.