Costa Coffee review: Abrasive attitude

whilst ordering 3 medium hazlenut lattes on Saturday the 23 November 2019 at about 12.15pm, the girl taking orders seemed distracted and was laughing, as were her 2 colleagues. they seemed to have found amusement in a previous customer. when a few moments later she advised her colleague what to make me she said small. i interjected and said id asked for medium. she verged on disputing this and was about to charge for medium saying id said small. i in forced id said medium. she was advised by another staff member to leave it and made them medium, which was fine, until the comment 'i just love Saturday's'
followed peels of laughter from all staff that made me feel very uncomfortable.
i think that rediculing customers and not paying attention to their orders is bad business practice. id feel uncomfortable going here again.