"Cancelled my important test because the doctor..."

I had an important test booked in Rheumatology today to find out what exactly is causing my pains I've had for 3-4months. I not only waited for a month after seeing the Rheumotologist Doctor to even get the appointment date through the post, but now on the day of the test thats I've been waiting anxiously for! I get a voicemail from a nurse saying its cancelled as the doctor has called in sick this morning! And now they will reallocate me another date which I will have to wait to come in a letter through the post! This is disgraceful! How come you have no other doctor trained to do this test? How come I have to wait so long? How come you cant give me a date over the phone?! Honestly what do I pay tax and national insurance for? So far I have had no answers about my pains.. I continue to work whilst in pain! And have to pay for all my medications that only take the edge off my pains! Ridiculous! You need to have better organisational skills and customer service!