I have specific products and services for a customer. I would like to run a report which shows me the products and services I have invoiced and which I haven't

Hello and welcome to the Community, garyjohnbuckley-

There is no single report to show this, however, you could customise the Sales by Product/Detail report and cross-reference this with the Product/Service List report. 

To customise the Sales by Product Detail report, select Customise > Filter > Tick Customer and select the relevant customer from the list, then Run report. 

If you would like to see further reporting options in QuickBooks Online, please consider leaving feedback on our Idea Exhange board. We'll be reviewing all ideas submitted here, and if it gets to over 50 votes, we will review it with our product team.