"mix up over appointments"

I was given an appointment for a heart monitor to be kept for 24 hours I arrived at mayday as requested on the letter on the 15th April but the receptionist was very apologetic and said they had put the wrong hospital on and I should have gone to Purley mistakes happen' so she made me an appointment for following week for the tues at 11 and wrote this down on a note for me, a week later I turn up on time as usual at 11 and am told I have no appointment I was disappointed again but the nurse asked the nurse concerned with this department if she could fit me in she said yes that was at 11 and I could see she had no-one in with her but I waited outside waiting to be called by 1140 another patient rolled up half hour late apparently and the nurse called her in I said to nurse id been waiting and car was on meter and didn't think I could wait anymore she told me she was doing me a favour by seeing me at all and rudely told me to wait to add insult to injury very unprofessional I couldn't risk a ticket ,so here we are I need a my heart to be monitored and don't know what to do next.