vodacom *****s my airtime claiming its airtime advances

I bought R17 airtime from vodacom R4.10 was deducted they claimed i did a airtime advances. I called their 082135 4 times and all i get is their useless self service (service) there is no call centre agent to assist me with my query. i procceeded to go to their website and chat with tobi service the agent on this end saiys he only deals with sales