SELS12 repositores are unavailable for PAYG instances

ok i believe your issue with accessing repositories has to do with the version of cloud-regionsrv-client you are running in your SLES 12 instances. Please see the following:
https://www.suse.com/c/suse-update-infrastructure-access-through-the-data-center/
https://www.suse.com/c/?s=cloud-regionsrv-client