How long does dbs stay at stage 4 and at what point on the online check would It show if I was on barred list ??

Stage 4 seems to be about your representations, so they should have given you a time limit. After that, it will probably be up to 28 days, depending on their workload. If someone is barred, it should show up on online checks once the barring letter has been generated.

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If you are to punish a man retributively you must injure him. If you are to reform him you must improve him. And men are not improved by injuries. (George Bernard Shaw)