Not happy with Vodacom

I had bad experience with Vodacom the past months. I do have a cell phone contract and got a new contract for a tablet during April 2018. My debit order for my cellphone contract is on the 15th of each month. I called Vodacom to find out when will the cellphone contract be debited from my account and they told me because it is "one" account, my cellphone and tablet will be debited on the 15th of the month. To my surprise I received a sms today (6 May) from Vodacom stating that my Vodacom debit order for R127.19 was returned unpaid. I am absolute in disbelief because I have contacted Vodacom to find out when will the tablet be debited and they specifically told me that it will be on the 15th of each month. I don't keep money in my savings account, only for my debit orders at the 15th of every month. This kind of things has a bad influence on my credit rating and I am for sure not happy about this. look into this matter because Vodacom is at fault with this debit order. Check my calls to your Customer Care