You're welcome, we ended up being two months due a while back after going to the SGK office to change our address, an unnecessary trip as it turns out as it is automatically updated when your RP is changed, and the girl told us we didn't need to pay until the following month - wrong durr - showed as owing 2 months when I checked on the TEB site. Up to date again now though.
We experienced the SGK system being "down" several times when we used the government banks to pay it, we found it is best to pay towards the end of the month at the little Vakif bank opposite Zakkums (as was), just down from the big Migros. But I must say doing it online is much easier. Try again in a few days.