Hello stepheen. Welcome to the Community.

I understand you have NS Flex. An NS Flex product payment is not going through the balance on the OV-chip card, this goes via direct debit. The product will be renewed every month when you don't end/change it. So for example if the NS Flex Traject Vrij started on September 1, it will automatically renew on October 1 and you'll get an invoice for that. Not using the product doesn't mean that we will end the product. You need to change/end it yourself. I understand you now switched to a different product. You do need to pay the invoice you have gotten with your old product on it. You have probably also gotten an email that we settled the refund of the old product with the costs for your new product. If there is a refund remaining that is probably settled with the open amount. There is now probably still an amount which needs to be paid. So I can only advice you to pay the remaining, open amount to us. If you have questions about this you can best contact our Customer Service.

Hi , I changed my bank account number to a new one and I have being waiting for my new account to be debited , I was emailed that my new bank account will be debited on the 1st of September but it wasn’t , how can I pay for my NS flex subscription with my new bank account after receiving my invoice? 

Mostly the date is not exactly 1 september, it may vary. When is not deducted at the sixth of september, Contact Customer Service. Do not worry.

When does the money be deducted from my account?

The money will be deducted from your account in the week after you’ve received your monthly invoice. The detailed invoice itself (which you can download as pdf in Mijn NS) mentions the date around which the money will be withdrawn.