Tier 2 visa extension rejected for wrong reasons (urgent help)

[Feranmi]

Hello, thank you for this forum i have got great advice on here.
I was on tier 2 visa from Feb 2016 which expired Feb 14 2019. My SOC code is 2472 and as at the time of my application the experienced rate was £23,600 (i have screen shots of the codes, it even says source: ASHE 2016)
I out in my application on the 14th of Feb using standard service and on the 10th of April my visa extension was refused
see reason below
From 6th of April 2013, a new policy on rates for new entrants and experienced workers within the codes of practice was introduced. the minimum acceptable rate of pay for a 39 hour working week for your prospective employment is £26,000 per annum as stated on occupation code 2472 under the experienced worker appropriate salary rate.
your certificate of sponsorship states that your salary would be £24,505 PA for a 40hr week which equates to £23889.84 PA for a 39 hour week. so no points awarded for salary.

Issue is this new rate was just introduced, it wasn't there in Feb 2019
The case worker has stated that the rules changed in 2013 again this is not true as i have checked all the archives and its not there.

I have being offered an administrative review which i think i would go for but what are my chances it would be successful?
Please can anyone help with how i should word the administrative review for success as i am certain the case worker used the most recent codes of practice
Also should the administrative review come back unsuccessful and i decide to make a fresh application
would it still be an extension?
would i need RLMT?
my company most like would not increase the salary but they can reduce the hours to say 36 hours, would this be okay?
would i be able to continue working when the fresh application is being decided?

I hope i am coherent, i just do not want to tamper with 8 years of legal stay en route 10 year ILR route

Thank you so much