I had a very similar experience with them half a year ago.
Before i bought the service i asked them if exits are allowed and how they act in case of abuses.
Their answer was that exits are allowed and they will find a solution together with me in case of abuses.
Three months later the second abuse was from a very confused admin because someone made posts with curse words in his forum and he said he always receive emails when someone made a post and thats the way he found out about it.
He did not even mentioned the affected IP address.
Contabo said i sent spam emails and blocked my server until i solved the problem.
I told them that no one sent spam emails and that they misunderstood the abuse report and that i will block the IP address if the admin will tell me which one.
Contabo said my answer is insufficient (their words) and that they won't unblock my server.
It got back and forth like that three or four times until they said that they will only unblock the server if i remove Tor so i asked them for a refund of the remaining 6 months because i asked them if exits are allowed before i bought the server.
They said no and showed me their TOS.
I switched it to a non-exit and told them that Tor is removed and they unblocked the server.
In March the service will finally expire and i can only recommend to stay far far away from them.
Sincerely