Erratic paying tenant – moving the rent date

I have a tenant who has been in a property of mine for 3 years with no trouble. 3 months ago decided to change from managed to un-managed and during the switch over the rent due on 5th September was delayed in arriving in my account, not arriving until 18th. The 5th October arrives and rent unpaid again. A courtesy text sent from me on the 20th to the tenant asking why and I get a response telling me unable to pay until 30th of October which to be fair it was. I have since sent an email requesting that a standing order be set up and whilst I am happy to change rent due date to suit his new need, I am entitled to have an over-payment to cover the fact that the due date has moved back about three weeks. 

No response from this for five days, don’t want to upset the tenant as he has never caused any grief but I feel justified in getting this sorted and being pro-active about it.

Any thoughts?

Thanks

Darren