Short upping of the speed when switching

Does one of you have any experience or advice about the following case??? 1.8 TT Roaster 45,000km Bauj 03.2001 180Ps motor original no tuning. When switching, usually at a speed of 3000 and especially in the first gear, the speed does not go down immediately when the coupling occurs, but by about 200-300 revolutions up and then falls down. This disturbs very much with sporty driving. But does not always occur. Ca 2 switching operations normal, then again one where the speed goes up. The dealer I have is very trusting and always has an advice and an open ear. Means that he really doesn’t find and know anything. I hope someone here knows a advice or even a solution. For quick answers I thank you in advance, because I’m slowly going to the cookie and I need a solution. L.G. Foxfire65