Team-BHP - Opel Corsa 1.4 Model 2001

I am a new member and in a bit of car trouble.

I have an Opel Corsa, which has done about 65 K km. The engine is abslutely fine, but I am feeling a loss of power suddenly (earlier occasionally, now frequently) and the car is not able to cross a speed of even 20 on 1st gear, with almost full throttle. I noticed this happening within 10 - 15 minutes of driving and in some cases, after passing over any bumps / speed brakers.

I got it checked from some local mechanic, other than Opel (as that is too expansive). He said it may be because of jammed brakes, adjusted and I test drove with him for about 4 km, without any problem.

The same day, when I came back from about 6 km drive in the evening I noticed a red glow below my car and was shocked to see that coming from some overheated part (below the gear lever or slightly behind that). Not sure if this is the gearbox, but this sure seems to be some serious trouble

Opel has a horrible resale and I am not likely to get more than 1L on this, so don't want to spend too much.

Need the following help from the forum:

- can some one suggest what can be the trouble
- what is your suggestion - should I try to find some local expert mechanic to get this repaired, even if I do, will Opel sell me the parts if I require.

Need a urgent help on this.