Car giving problems after tuning from mechanic

Hi,

I have an automatic city, 2007 model car. I got it tuned from a Honda sc yesterday. After I started to drive, It began to give me troubles. Here's what happened.
The Problem:
I pushed the accelerator half down abruptly(to cause a gear change), it went to about 3~4k RPM. And then when I released it, the RPM was still there. That is, it didn't come down. It got stuck at 2.5k. Speed was about 60kph. My immediate reaction was to press the brake paddle; as I did, I realized that the brakes are failing as well. By failing I mean the hydraulics system didn't work, so the paddle became very hard to press. Also the wheels weren't stopping very easily, I had to apply tremendous amount of force on the paddle to make the car come to a stop.
After that, I changed the gear from "D" to "P". As soon as I changed it to P, two things happened;
i) The RPM instantly went to very high rev 5.5k, which is the max I think.
ii) The gear was locked. I mean the button on the gear that you pull to change the gear, that didn't work. It seemed as if the action of "brake paddle getting pressed" didn't get recognized with the car and so the gear stayed locked.
And the problem persisted after I switched off and then switched on the car.

I called the mechanic and when he started, it started fine. Went for a drive of about 2~3km, and it was fine even then.
But when I drove again, I realized that the problem is still there; it just doesn't always occur. The frequency is low. Later in the day, for 1 hour and 30 mins drive it occurred only 5 times.

Also of importance would be to mention here that when this occurs, the solution is to quickly press and release the accelerator(about half down). This will make everything ok instantly. This can be done when the car is in D gear and moving, or if its in P as well.

Other information that might be useful:
1- The mechanic cleaned the brakes and the throttle body among other things.
2- The mechanic told me that its a routine matter and this problem usually clears up after driving about 30 kms. It definitely didn't clear up, But I thought I should mention it here.
3- I don't exactly know how to reproduce it, but I think it happens when you press the accelerator to the floor quickly and the rev jumps from ~1.5k to 3~4k and then you take your foot of the accelerator.
4- I dont think its speed related, it occurred between 20~40 kmph as well as 50~60kmph.

To summarize, 3 problems occur at the same time:
1- Rev gets high
2- Brakes fail
3- If I change to P, the gear would get locked and Rev would get to 5.5K.

I hope to get your reply soon. Thank you.

Regards
Asad