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?

Martin Guy
March 2011