Skoda Octavia Automatic Gearbox Fluid (ATF) Problems

Hi all. I am new to the site. When I am driving the car suddenly revs up but there is no gear change. I take my foot off the accelerator and let the revs die and then accelerate gently. That appears to do the trick. Any ideas as to what...

Cant put car into drive mode and it only moves on reverse when pressing gas , tried replacing the gearbox oil yet still same ,old oil was completely burned