Back billing clarification needed here

Thrilled

Thats why I'd want a near certain case before risking that 12 months.

MWT

Then take the 12 months and move on I'd say.

Never going to get close to certainty on a better outcome than that.

rp1974

Thrilled said:

Thats why I'd want a near certain case before risking that 12 months.

Which in all honesty it is unclear that you have,take the 12 months write off and move on from this and from the baggage associated with it.
Sometimes even though in principle you may be in the right,the time,effort and general hassles involved in disputing events isn't worthwhile,particularly when a perfectly reasonable alternative which you risk losing entirely has been offered.