Siemens Gagaset cordless phone set (Lewes BN7)

C430A cordless 4 phone set with answer phone. I upgraded because the phones seemed to be loosing their charge once removed from the cradles even when I replaced the batteries. They work fine in the cradles. I still have the batteries but no manual which can be downloaded from https://www.manuals.co.uk/gigaset/c430a/manual.