BILLING ERROR

MTN billed me for cancelled insurance twice. When lodged a complaint along with bank statement showing deductions, they want me to send them invoices, which they never sent to me. They blocked me from making calls so I have been communicating with them via email. Tried to call them with using another number and they telling me they are experiencing network problems, this is day 2 with network problems and a week for me not able to do any communications.