"Corrective surgery incorrect information"

After squinting for 58 years I was told that this could be corrected and was asked if I had any holidays booked. I advised that yes I did 2 weeks end July beginning If August. I was told in March I would get the surgery before this time and was absolutely delighted to think I could go on holiday this year without a squint. I now learn my surgery can be done 6th August? But I am on holiday that date so will have to wait and guess what if the last measurements were taken over 12 weeks ago - which will be the case then I may have have to make 3 further visits for exactly the same procedures to be done again. Why oh why did I ever trust the NHS so disappointed that yet again for another year of my life I will be the person with the sken eye on my holidays and choice is to cancel holiday or take the date which might not go ahead if further measurements needed? Seriously does the NHS have idea what they are doing! The patient charter says they have to deal with cases within 18 weeks but after 12 weeks for this operations new measurements may be needed so common sense would dictate operation needs to be done within 12 weeks! It's simple maths. 1 extremely disappointed let down upset aggravated patient. I wish I had never ever been told this could be put right,.