My daughter is visiting the UK from the US for a semester study-abroad program. Because it is less than 6 months, she doesn't need a Tier 4 visa. She arrived a few weeks before the program started in order to do some sight-seeing, staying with friends. She didn't notice right away, but the IO stamped her passport with a visitor stamp, rather than a short-term study stamp, even though she gave him the letter from the school. The school requires her to have the short-term study stamp. They have recommended that she either try to speak to an IO at Heathrow to get the correct stamp, or leave an re-enter the country.
If she were to visit Heathrow, how would she go about trying to contact an IO, given that they are stationed at the arrivals gate. Or, is there another way to go about this that doesn't involve leaving the country?