You should wait a few days for Facebook to check again and then you can use that account later. To avoid interruption of advertising campaign, you can replace the backup BM with a personal account. Recently, many BM accounts have been upgraded to BM2500 and BM10 by a tool, which is why many accounts are locked. Even old BM accounts can be affected, and this is especially unfortunate for those who have just bought upgraded BM2500/BM10 accounts by the tool.