hi sorry if i have placed in the wrong space but i am new to this,i have a renault scenic rx4 privalige 2001 model with 86000 miles on clock,my car has sounds like a disel once it reaches the half way point of the heating qiuet on start up been going on for 6 months now,just been toldthat it is the dephaser pully and it is gonna cost 500 ,struggling with this as mum of twins my question is i had the cam belt .timming belt and the tappits all replaced but they are saying i will have to have the cam belt done again as the dephaser pully needs doing?