The EPS '95 Pension calculation procedure by the EPFO, appears in an incorrect way

The EPS '95 Pension calculation procedure by the EPFO, appears in an incorrect way . They are calculating the pension in 2 spells, i.e. (1) the pension upto 31/08/2014 with the pensionable salary of Rs.6,500/-and (2) the pension from 01/09/2014 with the pensionable salary of Rs.15,000/-, which is against the procedure stipulated in the EPS '95 manual.
The EPS '95 pension calculation formula is as follows:
Pensionable Salary X Pensionable Service /70
Here the pensionable salary is, the average wages of the latest 60 months to the retirement date, which should be the one and only.
But they are following the methods, against the method stipulated in EPS '95 manual, to reduce the the monthly pension payout.
In this regard, I request the experts to disclose their valuable opinions/experiences.

Dear Mr Reddy,
The EPS '95 Pension Calculation Procedure is correct.
Let me explain you, as already mentioned above:-
"Here the pensionable salary is, the average wages of the last 60 months to the retirement date, which should be the one and only"
So as of now (30th Nov'18) if we count last 60 months, than it will be (Dec'13 to Nov'18). The Wage ceiling for EPS increased to Rs. 15000 (wef 01st Sep'14).
Hence the average wages of last 60 months will be :-
51 months @ 15,000/m (Sep'14 to Nov 18) = 15000/51*12
09 months @ 65,00/m (Dec'13 to Aug'18) = 6500/9*12
That will be average Wages for EPS Calculation = 12,196.
For more clarification let me tell you in respect of person who will retire on or after 01st Sep' 2019, the average salary will be 15,000 itself (If EPS contributing upto Wage ceiling amount).
Coz whole 60 months period will be related to Rs. 15,000 wages and pro rate calculation will not required.
Hope the matter is cleared now. I seek more expert (Specially Mr Abbas) views on the matter.

Dear Mr.Pan Singh Dangwal,
You have arrived the average pensionable salary as follows, which i can't understand.
The average wages of last 60 months will be :-
51 months @ 15,000/m (Sep'14 to Nov 18) = 15000/51*12
09 months @ 65,00/m (Dec'13 to Aug'18) = 6500/9*12
That will be average Wages for EPS Calculation = 12,196.
I feel that, it should be as follows:-
51 months @ 15,000/m (Sep'14 to Nov 18) = 15000*51=765000
09 months @ 65,00/m (Dec'13 to Aug'18) = 6500* 9= 58500
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823500/60=13725
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Thus the average Wages for EPS Calculation = 13,725
Please correct me if i am incorrect and also you have not given the clarification on the pension calculation system adopted by EPFO.
Please let me know that, the EPS pension calculation done in 2 spells is correct or not?