I agree with you, I think the Tribunal’s decision is wrong.
The Tribunal has made two mistakes I think.
First, it’s over-simplifying things to say “the claim” has been superseded: only individual decisions can be superseded, and separate changes of circumstance givce rise to separate superseding decisions. You need to look at each one in isolation where they run in a sequence over time.
Second, there is an important distinction between the date when a decisoin was [u:efe883644b]made[/u:efe883644b] and the date when it [u:efe883644b]had effect[/u:efe883644b]. See in particular D&A Reg 7(2)(a)(i).
Have a look at your original decisions as first made, in sequence, at all stages between May 2004 and August 2005. Consider whether each of them should be revised or superseded in the light oif the ninformation you received in August 2005. My betting is that you made a decision in April 2005 (supersession for the uprating) in ignorance of the fact that the claimant was no longer working. It was too late to revise it when you found out, so instead you made a superseding decision from August [start of the week you found out, I hope – Reg 8(4)]. You also made a superseding decision for the period from May 2004 up to the date when that decision ran out (I assume April 2005) and it caused an overpayment – disadvantageous change in May 04. Correctly, you allowed underlying entitlement from March to April 05.
Subject to a quibble about the week of the August 2005 superseding decision (start of same week, not next week) I reckon you have pretty much got everything right here.