Billing address still not changed after 5 months

I have moved from Witbank to Bronkhorstspruit and transferred my Telkom home line to the new address. Every month I view my bill online and the bill is still showing the old address. I've phoned Telkom every month for 5 months now to have this problem sorted out and every time they tell me it has been solved but I must wait for my next bill. Today I've checked the new bill and again the bill is showing my old address. I need this bill as proof of residence to claim transport allowance and for 5 months now I am losing money due to Telkom customer service not doing their work.