How can we improve WHMCS?

I just had a customer whose IIS SSL certificate (quickSSL) had expired in March, and the system automatically charged them and renewed the certificate.

Finally the customer asked me to install the new certificate today. Remotely connecting to their computer, I found that there is no "certificate request" at the IIS - obviously since it's a renewal.
On WHMCS product page, there is a CSR, but there is no Private Key. Without the PK I don't think I can re-generate the CSR at IIS.
I did try to insert the certificate that WHMCS product page was showing to IIS by using the "finalize certificate creation" or whatever it says. It seemed to ignore my finalize request.
So, I had to cancel the certificate at WHMCS, create a new CSR at IIS, upload it to WHMCS, and buy a new certificate.
I believe I will be charged twice now :(

Therefore WHMCS should not renew IIS certificates, at all.. Since IIS requires you to first create the CSR, and then click "Finalize certificate" button aftwards..