"Trying to cancel diabetic eye screening test"

For 3 days prior to my appointment I have been trying to cancel my appointment for the diabetic eye screening test due to domestic reasons. I have tried phoning the number on the letter countless times and always kept hanging on for a very long time until I have had to hang up. I have also tried other numbers and got put through to the same time wasting system. I have had two texts reminding me of the appointment which gave me an unobtainable website number, I have also tried numerous other NHS website numbers none of which gave me an option to cancel. The texts will not take reply calls. Unless I can find someone to stand in for me at home I shall have to fail to go to the hospital and so cost the NHS the amounts stated in the text. Why not make your telephone answering service more acceptable to cancellation calls and so save the NHS money in the long run?