How would you handle this situation with customer service?

first remain calm and do not raise your voice. they could just be trying to con you. you need to say something like 'you say your friend made a booking with us for $115 could you tell me their name and the date they booked for and i will check it' if you find after checking that there is no booking then you need to go back and say 'sorry ma'am but we do not have a booking here for your friend i suggest you check with her that it was this hotel she booked with' if however on the other hand you do find you have a booking and that the price at the time of booking was $115 then you need to discuss it with the manager to make a decision. if she had a booking and paid $150 then you need to go back to the caller and say something like 'i have checked and yes we do have a booking for your friend but it was for $150 not $115, i can only assume she misheard the price, do you want to make a booking or get back to me after talking to your friend' sorry this is so long but the main thing is to remain calm and polite the whole time and remember it can be very easy to mishear particularly with 115 and 150 - say it to yourself a few times and you will know what i am talking about. so long as you remain calm you are the winner.

You explain that she can be transfered to your supervisor, There are guidelines in place to handle these situations. Follow those guidelines.

I will give him free