My (ex-)wife and I had fellowship withdrawn when we chose to attend a different congregation. The small (seven member) congregation we had been attending sent us a certified letter with a bullet list and supporting documentation indicating how the new congregation was unscriptural and concluded that we were sinning by fellowshipping with an unscriptural congregation and that if we didn’t return and repent they would withdraw fellowship from us.
The absolutely hysterical thing about the whole situation was that when we left the first congregation we were essentially withdrawing fellowship from them. Not in the formal “scriptural” sense, but in a practical sense.
We didn’t go back to them.