Wrong milkshake and didnt even taste nice

last night 14/09/2015 around 7:30pm I ordered and chocolate milkshake and chai lattte at the drive -thru , we proceeded and waited a little longer than usual and collected our drinks and as we hit the highway I took the first sip and to my disappointment it didn't taste chocolate , it was actually a vanilla and a very bad tasting vanilla , i could have rather ordered plain milk . We were on the highway took the offramp specially to order a macdonalds drink , now this may be small to you , but i was very disappointed and because you already on the northbound highway you cant even complain to anybody . Now this just cements a culture that is projected by your drive -thru , so basically your drive -thru is useless to me . I couldn't complain to anyone on the highway , hence I'm complaining here so you can read it , if you you want to improve your organisational culture.