So I decided to play Dual Universe for a considerable amount of time after a long break. I was trying to get into space with a construct that I knew was able to get into space before. After a bit of trial and error, I realized I had to add a medium atmospheric engine to my construct into space. I was able to leave Alioth, and after getting to space I decided to go back to base in Sanctuary.
Little did I know that I had barely enough space fuel, both in the tank and in my inventory to make it to Sanctuary. After reaching space I turned around to set course for the moon. I realized I was slowing down from my initial course fast enough, but stupid me forgot to brake! I had less than 10 percent in the space tank after that ordeal and about 25 L total in my inventory, but I thought I still had enough. That was until I overshot Sanctuary and had to turn around yet again. I lost even more fuel. Upon turning around a second time, this time I remembered the space brake exists and this helped me with changing direction.
At around 10 su from Sanctuary (and 20 km from the edge of the safe zone, too!) and with about less than 3 percent in the tank, I decided to go at 25 percent throttle to about 3000 km/h, then shut it off. This time my ship was headed in the right direction. I let Sanc's gravity speed me up to about 4000 km/h, which happen when I was between 1-2 su from the moon. After making a gradual descent I made to Sanctuary and my base with around 1 percent space fuel left!
tl;dr: I almost got stranded in space due to my stupidity and lack of fuel, but a clutch performance helped me get to my destination!
I had a similar problem to yours but what I did was use the live chat option of Xsolla's website in order for them fix the problem. Talking with a customer service agent helped enable me to pay NovaQuark through their payment company.