Incorrect airtime recharge

By end of November 2017 I bought Vodacom airtime via cell phone banking and followed the right steps indicated on the cell phone only to find that the airtime I wanted to buy initially is the incorrect one . It also happened yesterday morning between 10m and 11: 30am the very same ting repeated itself. I selected the right option of R5 airtime which was option 1. Actually the options were as follows: 1. R5, 2. R10 just like that. But after selecting option one which was for a R5 airtime then a R110.00 AIRTIME AGAIN FOR THE SECOND TIME IN A MONTH. Something which I know that I did not choose. Please assist as I think one of the companies is a *****. The highest airtime I can buy is for R29 only NOT R110.00