Tim Hortons review: order mixups

I go to the thornton, on location on a daily basis. I order the same thing each day. At least once per week I get the wrong thing. Being on the road, sometimes I don't get to my order until i'm down the highway. I always check my food to make sure it is correct now, but my beverage is always the same. I give it a sniff test to make sure it is not coffee as I detest coffee. Well as usual, I order 2 xl st tea, both with 3 milk and 1 sweetener.

I only sniffed one today as I figure why would the other be different?
Well, just got to work, opened the first tea, which is marked as st. And low and behold it is coffee! So very disappointed as once I am at work, I cannot leave.
Why does this keep happening? There was no coffee ordered, lids state st, but one is coffee and the other one is tea.

I normally go back to get it for free the next day, but felt I had to let someone else know so that this doesn't keep happening. Getting tired of having to correct them, and feel like a beggar when I ask for it to be free.

Is there a training program that they go through? It does not appear that way. They should have to confirm orders with the staff who are making the orders before giving out to the customer. I know time is of the essence at the counter/drive through, but order accuracy should be more important.

Last time this happened, I received 2 coffee's, both lids marked st3m, 1sw. Are they that simple?
I would appreciate your feedback and hopefully something can be done.
Thank you
Sharon morrison