Thanks for (most of) the replys, as i said only wanted an idea of cost and the best option.
As it turns out Tony the eng didnt try sell me a new boiler as you expected and believe it or not I did have the common sense to ask if he was familiar with the make!
Boiler running away lovely...
hi having problems with my boiler which is vokera flowmatic 20-80 rs, hot water only works when central heating is on. realise the boilers old and prob better being replaced but need a short term fix to get me by just now. Thanks :)