Changed appointment without consent

I walked in-store to book for a wax and nail treatment for today at 4. The booking was confirmed. This morning i got a sms stating a different time of 4:30 as my start time. I then called the branch to check what the new time is all about. the lady then advised that there is no one available to start with my nails at 4:30, instead my wax would start at this time, followed by my nail treatment at 5. I then advised that this is not a good time for me because I have other pre arranged things to do. After throwing a bit of a tantrum, she said i should come at 4 and they would make a plan. I absolutely do not believe this, all that will happen is that I will need to wait at the branch, which has happened with a prior appointment I have made. I am very unhappy with this. I do not understand why an appointment is changed without being consulted, furthermore why it was accepted in the first place if it will not be honoured.