MTN shoddy service

I have not received an invoice on 6 Feb 2025 (for January) for my cell phone, but the money was deducted by debit order from my account. I have contacted MTN's business customer service a number of times and requested a copy of the invoice, but they just reply and tell me the invoices are not available yet and give me a reference number. It has been going on for almost a month and I have received no help.