I finally got a reply from my email
Thank you for your email
The April payment should have debited on the 1st April – but due to a direct-debit processing error, payments were processed a day early. We apologise for any inconvenience this might have caused.
Kind regards
Supporter...
Strange!
The following message to <paul.barber@bhafc.co.uk> was undeliverable.
The reason for the problem:
5.3.0 - Other mail system problem 550-'5.7.1 Command not allowed'