Citroen C2 1.4 VTR Automatic/Half Automatic BJ 2003 Problems

Good morning dear community, I bought my first car in March this year, a Citroen C2 1.4 VTR 73ps Bj september 2003 automatic/semi-automatic transmission. Since the original radio wasn’t enough for me, I had built a new radio, everything ran out. Suddenly the car just ran out at the intersection. He paged 3 times and went out. I turned the car off, did nothing. This happened to me 2 times. Then my friend and his good friend (both cars Me) said Chatroniker), that it would probably be on the radio. So the old radio was installed again and everything ran again 2 weeks without problems – until yesterday I just remained on the highway. He beeped again 3 times and did nothing, no gas, just jumped in the STEHEN into the 2nd gear, 1st gear could not put in at all, the engine did not even cry anymore. After 20 minutes a couple pushed me on the side stripes, again nothing went. After about 30 minutes he ran like r quite normal. So I continued on the federal road, again he paged 3 times (happily then I drove to the side in the grass) and went out. Again the same game from the front. My friend, my mother, father, and the good friend of my friend had already informed me on the highway. On the federal road finally my friend and his buddy arrived. After a total of 2 hours drive home I arrived at home. My friend drove the car, until home everything was good. Later he told me that they had stayed on the way to his screwdriver hall (20 min away) 2 more times. Afterwards they had found out a trick, they turned off the car, turned it on again, started the reverse turn, finally the first gear and he drove again. Both of them are from a gear damage, I bought the car privately. Does anyone know this problem, maybe had the same situation? Is it perhaps another problem? Thank you in advance for your answers.