Need Help Wrong colours printing

Hi guys

We have an HP L25500 and are using digital factory RIP.

Some colours just arent printing or the designs on screen are printin much darker

Printed a whole car wrap last week no problems the printed a sign no problems half hour later tried to print but the charcoal grey colour we want for background colour is comin out wrong everytime
Its printed with a greenish tinge a purple tinge and a brown reddish tinge.. im at my wits end had this printer almost a year n just wont run jobs smoothly

 

My printheads haven't done a lot of work at all. I thought about changing printheads but literally they are less than few months old