Sabre HE boiler - heating won't go off at programmed time, have to turn...

[??C???? ??? 2k?ii7]

...off at boiler, what's wrong ? Have to turn it to O for the heating to go off, and then I end up having to turn it on manually in the morning (otherwise it comes on all night), also keep losing pressure - no obvious leaks.

[Max Power]

Correct me if wrong but I think your boiler has a built it timer of the type with little pins you push in for the time you want to run your heating ? If so the timer is busted ,common fault ,but easy repair ,it should come out easy and replace easy as the connections are of a spade type ,you will pick up a new one at a boiler spares store , the loss of pressure with no signs may be due to a dodgy blow off valve ,as this is piped to out side check that it is not dripping outside unawares to you , if its ok than you have a leak , and your only way of finding it is follow the runs of pipe and look for it (under floorboards ) or air pressure test with listening equipment In concrete