"agonising colonoscopy"

I went to Doncaster Royal Infirmary for a colonoscopy and gastroscopy yesterday. I have had a gastroscopy previously (at Bassetlaw Hospital) where the procedure was painless and the sedation effective. Today, the sedation did not work (I was wide awake throughout, apart from when I used gas and air during the colonoscopy which did not dull the pain and made me feel sick and woozy). I retched several times with the gastroscopy (even though I was supposed to be sedated) and found the colonoscopy to be the most painful experience that I have ever gone through in my life. I definitely was not sedated (I can remember everything) and, even when I was in agony and screaming, I was ignored by the doctor whose attitude appeared to be that they would carry on regardless. I cannot believe that, as a hospital,you would expect a patient to be screaming in agony and just continue. I find this completely unacceptable and came home feeling like I had lived through a nightmare. Surely I could have had further sedation (the gas and air did not affect the pain). I normally have a high pain threshold and have given birth to children without pain relief.