Terrible Billing Mistake that is now my issue

I am with Discovery health medical aid and I went to Mellins almost 1 year ago. I was told that the claim for my glasses is broken up into portions. R4000 odd of which Mellins claims directly from my medical aid which is paid directly into Mellins account and a R2000 odd that I submit a claim for and I will receive this amount of R2000 odd paid into my fathers account and I must transfer it into Mellins bank account. I must explain that at the time my medical aid was set up that the my father's bank account received the funds as he had been the main member in the past. At a point (08 Nov 2016) I received an email from Mellins stating

"Good Afternoon Mr Rory

I have sent the claim through to your medical aid.

The total amount was R8418.37 They have paid us R4263.00 (Which is your medical aid limit for your spectacle.) The balance of R2554.30 will be what you have to claim for directly to your medical aid. NB// The 20% discount is taken into consideration already.

I have emailed your form through to them but they requested that you do the claim for extra savings yourself. May you please request the correct from directly from them either by email or telephonic. Email address: ********** Telephone number: *** May you also sign it off and send it to them directly and they will pay it into your account so you can pay us when you receive. "

After this email I claimed the R2000 odd personally and then asked my father to pay this amount to me. I was never aware that there would be an amount of R4000 odd also paid in his account as Mellins explained the process to be a direct claim and payment from the medical aid to Mellins (which it apparently to my surprise not the case) and on top of this they confirmed receipt of funds as seen in the email. Mellins then kept pursuing me for the full amount (and not the amount minus the R4263.00) and I fought this tooth and nail for the last year only to find that the R4263 was paid to my fathers account without my or his knowledge. It is completely unfair that I have to now approach my retired parents for this money a year later as Mellins completely *****ed this up. On top of this , Mellins are pursuing my wife for full payment of her glasses even though she was told that her Medical aid and Mellins had sorted payment. Had this not been the case she would have never taken the glasses. The canal walk branch's billing is useless. I feel that it is only fair that I pay the amount other then the R4263 as one can not go asking for the funds from a parent over a year later. I am now told it will be sent through to the lawyers :(