How do I politely tell a client I will stop providing my services if they don't pay?

As the title says...

I have a client who I have been providing my services to for over a year now. In march he made me do a massive job for him where he owed me a lot of money. 6 months later, I have only got 90% of that money.

To make it worse he's given me other jobs in between and he hasn't paid for any of those. The amount of money he owes me is piling up higher and quicker than what he pays me.

I need to tell him I will stop proving my services to him unless he pays me in full but I don't know how to tell him.

"Hi X,

Following up from my email dated XYZ, I'm still awaiting payment for JOB X which was completed on DATE Y. As per the agreement between us this is now overdue and I would be grateful if you could make payment so this work can be settled and we can move on to other projects."

If they don't make payment I'd email and advise them that other work is currently on hold until all the overdue payments are sorted.

They are just taking the P and will continue to do this until you push back.

The example above is just great. And you really need to politely but firmly state that if your services are not paid for, then, unfortunately, the cooperation between you will be terminated. Good luck