My Drive Strikes

Hello municipality, have the following problem. When I roll through the city my thickness normally switches up at approx. 50 kmh. For some time it is like this when I go off the gas shortly before switching it still bangs me in the gear and I mean literally bang. Sometimes it can also be if I hold it at low speed the gear jumps out but does not switch up. If I stand there then and have no gear in it. Can you do something besides generallüberho Does any of you happen to have something to trade around??? Mfg