Incorrect deduction

I have been with discovery for years and it seems to be going from bad to worse.

I recently added my 2nd child/newborn baby on to my medical aid after checking the 2019 contribution and speaking to an agent, discovery even sent me a letter in the post confirming my new contribution then charged me R858 more than what they should have. Once again discovery has failed me as a long term customer and has done creative deductions from my account. This is unexeptable, discovery will surely lose a customer