Hi, if you have already replaced the actuator fluid (aka Clutch fluid) and the transmission fluid as you said and you're still facing the issue, the first thing that I'll do is I'll get the quantity of the fluids checked, especially the transmission fluid as usually when it is filled less than the required quantity or sometimes more than the required quantity, it will perform abnormally and that includes slipping as well. There is a level-checker nut below the transmission oil compartment that you can remove and if that compartment is overfilled, the extra oil will be released from there.
If all the above failed, then, unfortunately, due to excessive heating of the transmission of your Vezel, there is a strong possibility that you have to get the transmission checked by some reliable mechanic, which in the worst-case scenario, has to be replaced with a new one.
I hope it helps.
