Still waiting on invoices and calls getting cut

I've been waiting for Billing Invoices from MTN since 30 March. They sent the original email without any attachments. I sent them numerous emails requesting to resend the email and with the first few I received a response saying they are looking into it and even one that said the Invoices were sent and should be received via email within 2 and 24 hours. Now after Many more emails, Complaints through their website and phone calls that get cut off, I have received nothing. I think its time to cut ties with this useless \Service Provider". They will be receiving partial payment for partial services up until i receive up to date invoices."""