Bathroom drain broken, looking for a plumber to replace it

Hello, The plastic drain in the bathroom, the "douchebaksifon", is broken. The elbow-shaped connector underneath has come out of its place. I am looking for a plumber who will replace this part and do the insulation. The hole diameter is 90mm. If necessary, I can order a new drain part. However, the problem first needs to be identified. Thank you.