Vodacom sharing other customers' personal information via email

After complaining for years and multiple emails and calls, this seems like the last resort. Vodacom, I am receiving on average 2 emails per month with other customers' invoices, statements, itemised billing and payment overdue letters. This is not acceptable as it contains personal information. I would also like to understand how my email address is logged against these accounts - do you have system issues? I have raised this probably since 4 years ago with no resolution.