What are good tips for an oven that is too hot at the bottom? I am cooking various food at home in a new oven that I am kind of stuck with. We're renting and this is the only oven we have at the moment. It has four gas stoves at the top.

The oven is fan assisted but it is a cheap fan and an old grill and oven. Daewoo Cooker DCG5050SI

Basically it burns all my baked dishes. Burns the bottom of the cakes. I always make brownies, cookies and various cakes and no matter what I have tried--the different shelf rack, placing an extra tin. Nothing helps. My cakes always burn at the bottom.
What are some tips to prevent this? I've even tried to cut the cake half way or at the end - and ended up with messy food.
I'm a person that goes on vacation and bakes bread. As such, I have met a few terrible ovens around the world, and temporarily improved most of them to work better...

Grab a roll of aluminum foil (heavy duty is nice if you have it, or if you don't have any are are buying a roll with this in mind.)

On the bottom oven shelf, come in a few wires from the sidewalls (to allow some air circulation) and crimp on one end of a long sheet of foil - this sheet will be shiny side down, hung below the shelf, and attached to the shelf again in a similar location on the far side of the oven. You'll probably need two sheets (one for the front, one for the back) and should leave a similar small gap at front and back for some circulation, while keeping the centers tight or overlapped.

You can get much of the effect (but not quite as well, or as "semi=permanently") by putting foil, shiny-side down, on the bottom of your baking pans. If either is is not enough by itself, do both. It should help a lot.