"Waiting lists"

I am writing on behalf of my Dad who is waiting for an ankle replacement and has been on the waiting list since last May. Every time he calls to find out when his operation maybe he is told the next month this has been happening since December. We are very disappointed to have been told today that it won't be until April, last month they told us March. My Dad is a self employed builder and has been trying to plan his workload around his operation but it is impossible, he has now run out of work as he is unable to start any new jobs incase he gets called in. This is not ideal when going into a period of 4-6months of post op recovery on statutory sick pay. If he is eventually called into have his operation in April, he would have been on this waiting list for 11 months, surely this is unacceptable?