RW89 timer?

I have the above timer on my central heating/hot water system but have no instructions on how to operate it as it was here when I recently purchased the property. I have contacted Ideal Boilers with whom I have a maintenance contract, but they will not come out except in an emergency. They said to make sure the timer was set correctly. I can only get hot water using the immersion. The pipes are roasting, its dangerous to touch them and the jacket round the cylinder is melting. Any ideas?