Remote timer bps242rf how does it work ??? ?

Hi please can somebody help I've got my timer to come on from 6.30-8.30 on a morning which it comes on but when I set it to come on at 3.30-5.30 tea time it doesn't come on.
I have the sun (comfort mode on 22) and the moon one ( energy saving mode ) at 10. Could that be why is it because through the night the temp drops so comes on in the morning and throughout the day the temps warm so doesn't letter the timer kick in ?
Also I have the slider set to auto what do I do to have the heating on continuous if it gets cold ?
Also another thing can I just set it to come on once ? And what do I do when I go on holiday as I don't want turn the boiler of ? Any help would be greatly appreciated as the instructions are to complicated to understand.