I assure you this won't happen again.

Meaning

Giving a guarantee that the issue will be resolved.

Examples

• John: 'This is the second time this has happened.'
• Alice: 'I assure you this won't happen again. We've taken steps to prevent it.'
• John: 'I assure you this won't happen again. We are reviewing our billing process.'
• Alice: 'I've received multiple incorrect invoices.'