confirmation of income e-mail not recieved

My parentts are pensioners and members of Bonitas Boncap. Their contributin for 2015 is suppose to be R2301 per month, but due to forms that they were unaware of they needed to submit as proof of income they had to pay R833.25 extra that was deducted for March and now April 2015. i feel this is unfair, since the e-mail address that Bonitas used was incorrectly captured on the system and therefore did not reach them. this was not their fault. the sms's sent also did not have the form attached they are not that good with technology. So hence that they were unaware of the completion of such a form. the form was received on 16 March and submitted again with all documentation by 27 March. Bonitas did not indicate the they are willing to give them back or deduct the R833.25 from their next contribution. They are only acccepting the proof of the income effective from 1 May 2015. So for April the extra R833.25 must still be paid.The least that they can do is to acknowledge there was a mistake and to make up for the unnecessary R833.