Garage business really struggling

I have a client operating as a garage business, carrying out all manner of motor repairs.  They are really struggling and don't seem to make the kind of profits

that fit with the amount of work that they do.  They do offer credit, which has more to do with them not being able to get the bills prepared by the time that the

customers collect their cars than anything else (but is dire for cashflow).  They now have a credit card machine which really took some persuading.  

They seem to have issues with tracking billable hours.  I have devised a time sheet that includes all workshop employees and only covers one day.  This way they can see on a daily basis the combined billable hour figure, and identify problems as they go along.  Obviously, I am struggling to get them excited about this.  

So, I just wondered what other accountant's experiences are of garage businesses.  The premises is owned, so its not even as if their is rent to pay. 

I am also interested in what the average mark-up of parts is across the country.

This is my local garage - I need it to work!