Hi,Recently renewed the battery,ok for 1week& half,the alternator Pix came up on dash ,I renewed that as well,ok for same amount time,Battery constantly flattened,has checked all fuses and wiring,cannot find the cause.will you Help me please,It Is Audi a3 2002 1.9 tdi ,i know car is old but Why has this happened,after charge battery,turned engine,very very frustrated