Terrible service from Vodacom

I need to upgrade my cell phone contract. I have been with Vodacom for 27 years now. There has never been a problem with payment from my side. My latest payment shows on their system, but it is not updated to my account and now I can't upgrade. The closest Vodacom shop for me is approximately 50 km from my house & business. I visited the Vodacom shop 3 times already. Every trip is at least 100km travel and a minimum of 2 hours away from my business. Various phone calls have been made and each time a consultant advises me that they will escalate the query and the situation will be resolved within 2 hours. 6 days later I am still struggling to get this rectified. This situation is utterly unacceptable.