Aardvark Bouncy Castles

i have a 3 series 2 litre deisal tourer.w reg,i have just paid £1000 for a new fuel pump,and now it starts everytime 1st time in a morning but if not started within 2/3 hours it wont start?,i have to leave it overnight to start again,i use all my battery but in the morning it will start 1st key?,please can anybody help as i love my car and i have been told by my garage who fixed it that a decoke would siolve it at a cost of £300..can anubody help me,thx.bry.