I will submit a Premium Services proposal for you with regard to the robust letter.
Meanwhile, something along these lines “in respect of your purchase of my share of the practice, it was agreed that you would pay £3000 per month (£1500 each) monthly from July 2015 until December 2016 with the balance being paid thereafter.
In spite of agreeing this, you have failed to make any payment since May 2016 and the £5000 promised at that date has not materialised.
Whilst I hear what you say with regard to financial difficulties, that is not an issue.
You are now in breach of the agreement and whilst I would rather not have to instigate legal proceedings, it is beginning to look like I have no choice.
To avoid any unpleasantness, and to move this forward as quickly as possible, can you please make sure that you let me have all the payments up-to-date, by return and also let me have post dated cheques in respect of the remaining payments and the full balance due from now until December.
Can you please get back to me no later than this Friday, 12 August.